Repair or replace: how the decision is actually made

The first check is not the lock

Doors move. Timber takes up moisture through a wet summer, hinges settle under weight, and a strike plate that lined up two years ago can be a couple of millimetres out today.

One test settles it: does the lock work freely with the door standing open? If yes, the mechanism is healthy and the alignment is not. That is an adjustment, and it should cost a fraction of a replacement.

What makes a repair worthwhile

The body of the lock is sound and the fault is isolated — a spring, a cam, a follower with play, a cylinder that has never been properly cleaned. All serviceable.

Repair also wins when the existing hardware is better than what would replace it. Older mortice locks are often heavier and better made than a budget modern equivalent, and rebuilding one is both cheaper and a better outcome.

What makes replacement right

The lock has been forced. A mechanism that has taken an attack can operate normally while having lost much of its resistance, in ways not visible from outside.

Wear is general rather than specific — the whole thing feels loose rather than one action failing. Parts no longer exist. Or the lock was never adequate for the door, in which case repairing it restores a standard you did not want in the first place.

The option people skip

If the mechanism is fine and the real problem is that you cannot account for who holds keys, neither repair nor replacement is the answer. Rekeying is — and in a development with hardware restrictions it is usually the cleanest route as well as the cheapest.

Questions worth asking

What specifically has failed? A straight answer names a component. Have you checked it with the door closed as well as open? Would it be repairable if the alignment were corrected first?

Vague answers to any of those are a reason to get a second opinion. A locksmith willing to adjust your door instead of selling you a cylinder is generally the one worth keeping.