Vintage Mortise Lock Service: preparing for the visit

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

Does the deadbolt throw fully with the key or the thumb-turn? Is the trouble worse with the door closed than with it open? Do you own the home or rent it, and who should receive the keys?

The lock works with the door open but not when it is closed. Is the lock broken?

Almost certainly not. That pattern means the door has moved in its frame so the latch and bolt no longer meet the strike squarely. Solid wood doors in older houses swell in humid weather and settle on their hinges over the years. The service adjusts or shims the strike and tightens or packs the hinges so the bolt throws without lifting the door, and the lock itself is usually cleaned and lubricated at the same time.

What if the case is too worn to repair?

Then a replacement case goes into the existing pocket. Reproduction mortise cases are made in the common vintage sizes and backsets, and a modern mortise case with a cylinder fits many old pockets with minor trimming. The locksmith measures the case height, depth, backset and trim spacing before ordering, aiming for the new case to drop in with the original knobs and plates going back on, though a small pocket trim or fixing change is sometimes needed. Cutting the door for a different kind of lock is the last choice.