Vintage Mortise Lock Service: what to note first

The brass knob on the front door of your century home turns, but nothing happens on the other side. The latch stays tucked in, the door swings free, and the only thing holding it shut is the deadbolt and a bit key that has worn down to a nub.

Worth answering before the call

Can you send a photo of the plate in the door edge and one of the keyhole? Is the deadbolt keyed from the inside as well as the outside? How many keys do you have, and do any of them work?

Is it worth repairing an old mortise lock instead of replacing it?

Usually, yes. The mechanisms are simple and robust, and what fails is nearly always a spring, dried grease or wear on one part, all of which are repairable on a bench. Replacing the lock with a modern cylindrical set means boring a large hole through the door stile and filling the old pocket, which is more work and changes the door for good. A rebuilt case keeps the original trim and keeps the door intact.

Does a rented home need the landlord involved for this work?

Repairing a lock so it works as before is ordinary maintenance, but anything that changes who can open the door, such as a rekeyed cylinder or new keys, is something a tenant and landlord are expected to agree on and share keys for. The locksmith asks up front who should receive keys and can leave a note of what was done for the property manager, so both sides know what is on the door.