In short:
- Many lock faults are not in the lock at all. A dropped door, loose hinges or a misplaced strike plate can make a healthy lock misbehave, and fixing the door is cheaper than replacing the lock.
- Replacement usually makes more sense when the lock shows signs of forced entry, when parts aren't available, when keys are unaccounted for, or when you want a higher security level than the lock can offer.
- "Replace" doesn't always mean the whole lock. A euro-profile cylinder can be changed without touching the bolt mechanism, and some multipoint locks have replaceable centre cases.
- Photos of the lock's faceplate, the key and the whole door help a technician tell you which option is realistic before the visit.
Why there's no single answer
When a lock starts sticking, slipping or refusing to lock, most people ask one question: "Can it be fixed, or do I need a new one?" The honest answer depends on four things, and a technician has to look at all of them together:
- Where the fault really is: in the lock mechanism, in the key, or in the door and frame around the lock.
- What condition the lock is in: worn, damaged by force, corroded, or basically sound.
- Who has keys: whether every key is accounted for.
- Whether the lock is good enough for that door: its security level, and whether parts for it are still available.
A repair that fixes the symptom but leaves you with a worn lock, an unknown number of keys in circulation or a door that will drop again isn't good value. Equally, a new lock fitted to a door that has dropped on its hinges will soon show the same fault. The rest of this guide explains how each factor is weighed, so you know what to expect when you ask for an assessment.
First question: is it the lock or the door?
Locks are often blamed for problems that start elsewhere. ASSA ABLOY's product care guidance for South Africa points out that faulty hinges, warped doors and distorted frames "can put excessive load on other components", reducing their operating life. In practice that means a bolt rubbing on its strike plate, a latch that only catches if you slam the door, or a multipoint lock that needs a hard lift of the handle before the key will turn.
You can do a safe, non-destructive check yourself. Open the door, make sure it can't swing shut, and operate the lock with the key and handle as you normally would. Watch the bolt and latch move out and back.
- If the lock works smoothly with the door open but is stiff or won't lock with the door closed, the problem is most likely alignment between the door and frame. That is usually an adjustment, not a new lock. Our guide to a door that locks when open but not when closed covers this in detail.
- If the lock is stiff, rough or slipping even with the door open, the fault is in the lock or the key. Read on.
Don't keep forcing a lock that resists. MACO's user manual for its multipoint door locks warns that excessive force on the handle will damage the handle or the lock mechanism, and forcing a stiff key is a common way to snap one. If a piece of key is already stuck inside, see our guide to a broken key in a lock.
How the decision is usually made
The table below sets out the common situations and the usual direction of travel. It's a guide to the reasoning, not a diagnosis: the same symptom can have different causes on different doors.
| Situation | Usually | Why |
|---|---|---|
| Lock works with the door open, not when closed | Repair or adjust | The lock is usually fine. The strike plate, keeps or door hang need adjusting. |
| Stiff or gritty key, lock otherwise sound | Repair | Dirt or a dried-out mechanism can often be cleaned and lubricated with a product the lock's maker approves. A worn key may also be the cause. |
| Key turns but the bolt doesn't move | Depends | A broken cam, tailpiece or internal part may be replaceable on some locks. On others the lock case has to be changed. |
| Visible damage from forced entry | Replace the damaged parts | MACO's manual says that once traces of forced use are visible, the lock or handle must be replaced. Damaged parts can fail later even if they still work today. |
| Keys lost, stolen or unaccounted for | Replace the keyed part | Repair doesn't change which keys operate the lock. On a cylinder lock, a new cylinder may be enough. |
| Parts no longer made for that lock | Replace | A repair that relies on parts you can't get isn't a repair. |
| You want a higher security level | Replace | Security grade is designed into the lock or cylinder. It can't be added with a repair. |
| Lock heavily worn after years of daily use | Often replace | Fixing one part of a worn mechanism may simply move the failure to the next part. |
The factors in more detail
Damage and wear
Locks are designed for a finite amount of use. The European cylinder standard, EN 1303, grades durability by the number of test cycles a cylinder has to survive (for example 25,000, 50,000 or 100,000 cycles, according to ASSA ABLOY's technical summary of the standard). A front-door lock used many times a day for years can reach the point where several parts are worn at once. A technician looks at play in the key, slack in the bolt, wear on the latch and whether the handle springs still return properly.
Damage from force is treated differently from ordinary wear. A bent bolt, a cracked case, a cylinder that has been twisted or gripped, or a split door edge around the lock all count. If you've had a break-in or an attempt, our guide to lock damage after a break-in explains what to check and what to photograph.
Key control
No amount of cleaning or adjustment changes who can open the lock. If you've moved into a new home, lost a bunch of keys, or had staff, tenants or contractors leave with keys, replacement of the keyed part is the only way to make the old keys useless. Our moving-house lock security checklist helps you decide which doors to prioritise.
Security level
Lock security is built in at the design stage. In South Africa, lever locksets are commonly sold with two, three or four levers; ASSA ABLOY lists two-, three- and four-lever Union locksets carrying the SABS mark. The British BS 3621 standard, which Union describes as the basic thief-resistant standard for external residential doors in the UK, calls for five levers on lever locks. For cylinders, EN 1303 grades key security and attack resistance. If the lock on an outside door has a low security level, a repair keeps that level. Replacement is the opportunity to choose a better one.
If you have home insurance, check your own policy wording for any requirements about locks, and ask your insurer if anything is unclear. Don't assume a particular grade is or isn't required.
Parts and compatibility
Some locks have spare parts: springs, cams, followers, strike plates, handle sets, and on multipoint locks sometimes the centre case (gearbox). Others are sealed units, discontinued, or made by companies that no longer supply parts. Whether a repair is possible often comes down to identifying the make and model, which is why the brand stamped on the faceplate matters.
Cost over time
A simple adjustment usually costs less than a new lock. A major repair on a worn, low-security lock can cost close to a new, better one, and leaves you with an old lock. A technician should explain both options before work starts. Our guide to what affects the cost of a mobile locksmith explains the general price factors. Call-out: R250 call-out fee. Quotations: The technician assesses the job on site and gives you the price before any work starts. Nothing is done until you agree.
Partial replacement: the middle option
Between "repair" and "new lock" there is often a third option: change only the part that needs changing.
- Euro-profile cylinders. On doors with a euro-profile cylinder, whether in a mortice lock case or driving a multipoint lock, the cylinder is held by a single fixing screw through the edge of the door and can be changed without altering the bolt mechanism. That is often the most direct answer to lost keys or a worn cylinder. The replacement has to match the existing length on each side and should fit flush or nearly flush with the handle or escutcheon.
- Multipoint centre cases. If the central gearbox of a multipoint lock has failed but the long locking bar, hooks and rollers are sound, a matching centre case may be available for some makes. It has to match the original's backset, centres and fixing positions.
- Strike plates, keeps and handles. Worn or misaligned strike plates and keeps, and handles with broken return springs, can be replaced on their own.
Partial replacement only makes sense if the rest of the lock is in good condition and suits the door. If the lock case is worn or was damaged by force, a new cylinder alone won't fix it. Our guide to mortice, cylinder and multipoint locks explains how the parts fit together.
A simple way to picture the decision
The order matters. Damage from force and key control come first because they are about security, not convenience. Alignment comes next because it is the most common cause of a lock that "won't lock" and the cheapest to fix. Only then does the question of repairing versus replacing the lock mechanism itself arise.
What makes things worse while you decide
These are the most common ways a repairable lock becomes a replacement job:
- Forcing the key or handle. Extra leverage bends keys, snaps them in the lock and breaks internal parts.
- Spraying any oil you have to hand into the lock. Lock makers disagree about lubricants. ASSA ABLOY's South African care sheet recommends graphite powder for cylinders, while BASI tells owners not to use graphite in its cylinders, and Gainsborough says not to use oil or aerosol lubricant in its cylinders. Use what your lock's maker specifies, or ask a locksmith.
- Taking the lock apart. Springs and small parts are easily lost or put back wrongly, and some locks can't be reassembled without the right tools.
- Filing the strike plate or chiselling the frame to make a bolt fit. It hides the real cause, often a dropped door, and weakens the frame.
- Carrying on using a lock that is getting worse. A lock that fails in the locked position can leave you shut out or shut in.
What helps a technician give you a straight answer
A few photos and details often make it possible to tell you before the visit whether repair is realistic. Send them when you call or on WhatsApp:
- The faceplate on the edge of the door, close enough to read any brand name, model number or standard mark stamped into it.
- The whole door from inside and outside, showing the handle, keyhole and any second lock.
- The key, both sides, including any brand name or number on the bow.
- The strike plate or keeps on the frame, especially if you can see rub marks.
- What the door is made of (timber, aluminium, steel, uPVC or composite) and roughly how old the lock is.
- Exactly what happens: when it started, whether it's worse in hot or wet weather, and whether the door-open test above made a difference.
- Whether all keys are accounted for, and whether there has been any attempted break-in.
If the answer turns out to be a new lock or cylinder, see lock replacement in Sandton; if it's an adjustment or part repair, see our lock repair service. Either way, a mobile locksmith in Sandton can assess the lock, door and frame together on site, which is where these decisions are most reliable.
Questions
Is repairing a lock always cheaper than replacing it?
Not always. Adjusting a strike plate or freeing a dirty mechanism is usually cheaper than a new lock. But a major repair on a worn, low-security lock can approach the cost of a better new one, and you'd still have the old lock. Ask for both options before work starts.
If I've lost my keys, can the lock just be repaired?
No. Repairs don't change which keys open the lock. To make lost keys useless, the keyed part has to change: the cylinder on a cylinder lock, or the lock itself on many lever locks. See choosing a replacement lock that fits the existing door.
Can a lock that was damaged in a break-in be reused if it still works?
It's not advisable. Parts that have been forced can be weakened or distorted even if they still turn, and MACO's own manual says its door locks must be replaced once traces of forced use are visible. Have it inspected rather than relying on it.
Need a locksmith to look at it?
If this hasn't solved the problem, our lock replacement service covers it. We're a mobile locksmith in Sandton, so we come to your door.
Sources and further reading
- ASSA ABLOY South Africa: Product Care and Maintenance (PDF) — Faulty hinges, warped doors and distorted frames load other components; graphite powder recommended for cylinders and lever locks
- MACO: Operating and maintenance instructions for door locks, end users (Doc. 757585) — Excessive handle force damages the mechanism; replace the lock or handle once traces of forced use are visible; adjustment by a specialist
- ASSA ABLOY DACH: Technical requirements, DIN EN 1303 (PDF) — EN 1303 durability grades in test cycles, key security and attack resistance classes
- Union: What are BS3621 locks? — UK thief-resistant standard for external doors; five levers, bolt throw and key differs
- ASSA ABLOY South Africa: Union locksets — Two-, three- and four-lever and euro-profile locksets with SABS approval
- Wikipedia: Euro cylinder (pin tumbler lock types) — Euro-profile cylinders can be changed without altering the boltwork
- BASI: Fitting and care advice for locking system cylinders — A cylinder maker that says not to lubricate its cylinders with graphite
- Gainsborough Hardware: Care and maintenance — No oil or aerosol lubricant in the cylinder; graphite on the key if sticky