Common reasons a door lock stops working

The door moved

This is the biggest single cause and the one most often misdiagnosed, which is why it leads every door and lock assessment we do. Doors expand and contract with humidity across the year, and hinges settle under weight. A bolt that seated cleanly in March can be fighting its keeper by August.

The tell is simple: does the lock work freely with the door standing open? If yes, the mechanism is fine and the alignment is not. Forcing it in that state is what eventually breaks the gearbox on a multipoint lock, which converts a cheap adjustment into an expensive replacement.

Dust, then water

Highveld summers push very fine dust into everything, cylinders included, and it is the single reason outdoor gate locks here seize faster than anything indoors. On its own it is a nuisance. When the first serious rains arrive, that dust becomes a paste that grinds against the pins every time the key turns.

This is why locks so often start misbehaving at the change of season rather than gradually. Cleaning and correct lubrication at that point usually restores normal operation entirely.

The wrong lubricant

Oil-based sprays are the most common self-inflicted lock injury we find on a lock repair. They work beautifully for a fortnight, then attract dust and set into exactly the paste described above. General-purpose penetrating sprays are the usual culprit.

Locks want a dry lubricant. If a cylinder has already been oiled, it generally needs cleaning out rather than more lubricant on top.

Worn internals

Springs weaken, cams round off, followers develop play — and on the older doors around Morningside and the suburbs near it, all three at once. On a busy door this is ordinary service life rather than a fault, and much of it is repairable with parts rather than a whole new lock.

The distinguishing feature of genuine wear is that it is general — the whole mechanism feels loose or sloppy, rather than one specific action failing. Isolated faults are repairs; general wear usually is not.

The key, not the lock

Keys wear too, and a worn key in a healthy lock produces symptoms identical to a worn lock — which is why a lock repair in Bryanston starts with the key rather than the cylinder. If you have several keys for the same door, try another one — if a different key works noticeably better, the first key is the problem.

A bent key is a separate warning. It means force has been going into it for a while, and it is usually the last stage before the key snaps in the lock.

What this means for you

Before assuming a lock needs lock change, check three things: does it work with the door open, does a different key behave differently, and has anyone sprayed oil into it. Those three questions resolve a large share of callouts.

None of it is urgent while the door still locks. All of it is cheaper now than at the point where it does not.

The Highveld year, in the order it happens

There is a seasonal rhythm to lock failure in this part of Johannesburg, and once you know it the clustering makes sense. Locks here do not fail at random through the year; they fail in batches, and the batches follow the weather.

From about May the air goes dry and dusty. Fine grit works its way into every cylinder that faces outward — front doors, security gates, pedestrian gates, garage side doors — and accumulates quietly for months while everything still works.

Then the storms arrive from October and wash that dust into a paste. A cylinder that has been collecting dirt since autumn gets a soaking, and from that point the paste grinds the pins every single time a key turns. Wear that should have taken a decade happens across two seasons, which is why so many Bryanston callouts arrive in the same fortnight.

Grid outages and the locks nobody connects to them

It is not obvious that power cuts damage locks, and for a cylinder they do not. For everything motorised on a property they very much do, and in a suburb where almost every house has a driveway gate that matters.

A gate motor runs off a battery that is supposed to be topped up between cycles. Long or frequent outages mean it spends hours drawing down and never reaching a full charge, and a battery that never fully charges ages far faster than one on stable supply. That is why gate failures arrive in clusters after a bad run rather than at a sensible interval.

The same applies to anything electronic on a door. A keypad or a coded cylinder keeps working on its own batteries, but anything relying on wifi or a hub loses its remote functions the moment the power goes — which is the entire argument for the hybrid arrangement described on the smart locks page.

Complexes, builder-grade cylinders and the five-year mark

There is a pattern across the newer complexes in Paulshof, Magaliessig, Douglasdale and Fourways that is worth naming, because residents tend to assume they have simply been unlucky.

Developments are finished with hardware chosen on price, which is a reasonable commercial decision and has a predictable consequence. Builder-grade cylinders commonly start giving trouble at around the five-year mark, and because every unit was fitted at the same time, they start giving trouble at roughly the same time as each other.

If your key has begun needing persuasion and your neighbour has just had theirs looked at, that is not a coincidence and it is not bad luck. It is a cohort reaching the end of its service life together, and it is usually a straightforward lock repair or upgrade rather than anything dramatic.

How to tell which of these you have

Four causes, and a short sequence of checks that separates them without any tools at all.

Open the door fully so it hangs clear of the frame and work the lock with the key. Smooth with the door open and stiff when closed means the door has moved and the alignment is out. Stiff either way means the problem is inside the cylinder — dust, wear, or the wrong lubricant applied at some point by somebody trying to help.

Then look at the key itself. A visibly bowed or worn blade is a key at the end of its life, and a new one cut from the lock may be the whole answer. If none of that fits and the lock simply feels gritty and loose, the internals are worn and it is a replacement rather than a service. Either way, the Bryanston locksmith services sets out which job is which.

What it means for the way you look after a door

Pulled together, the four causes point at a maintenance routine that takes almost no time and prevents most of what we get called out for.

Once a season, work every lock on the property including the ones nobody uses, and notice anything that has changed. Once a year, clean and lubricate the outward-facing cylinders with a dry lubricant made for locks, which on the Highveld is the single highest-value thing anybody can do for their hardware. And whenever a door starts needing a lift or a lean, deal with the alignment rather than the lock.

None of that is specialist work and none of it needs a technician, though it is folded into any book a locksmith in Bryanston at no real cost. What it prevents is the version where a mechanism that had been complaining for a season finally stops on a night when it is raining.

What to tell a locksmith on the phone

Because most of these causes are diagnosable from a description, the five minutes before you call are worth more than they sound.

Say what the lock did before it stopped, not just that it has stopped. A key that has needed more force for a fortnight, a handle that has to be lifted, a door that only locks if you lean on it — those are the diagnosis, and a technician who hears them arrives with the right things on the vehicle rather than making a second trip.

Then photograph the cylinder and the edge of the door and send it. A picture answers more than five minutes of description and means the price quoted is the price that holds. A fair number of enquiries end on the message thread without a callout at all, which is book a locksmith visit.

When it is the lock after all

Having spent this article arguing that it usually is not the lock, it is only fair to describe the cases where it genuinely is.

The clearest is play. If the key can be waggled sideways in the cylinder while it is inserted, or if it turns with a loose, gritty feel rather than a definite one, the internals are worn rather than dirty. A cleaning will make no difference to that.

The second is a mechanism that has already been forced, whether by an attempt on the door or by somebody putting a great deal of weight behind a stiff key. Once tolerances inside a cylinder have gone, they do not come back, and the honest answer is lock replacement rather than a service that will not hold.