Mortise locks are those old-fashioned narrow latch units tucked into the front edge of a door. They can stick, come loose or just stop working with age. Trying to repair one generally is more trouble than it is worth, and modern replacements are easily available at any hardware store. For all the strength of a mortise lock, it is usually surprisingly easy to get one out of a door.
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Things you need
- Allen wrench set
Remove one doorknob by taking out the screw that secures the knob to the threaded stem. The screw will require either a small flathead screwdriver or Allen wrench.
Pull the other doorknob out, taking the stem with it.
On the front edge of the door, remove the two screws holding the narrow metal plate to the wood.
Pull the mortise unit forward out of the door. If it does not slide out easily, put your screwdriver through the hole where the doorknobs were and use it to pry the lock forward until it comes out.
Take the unit to your local hardware store to find a replacement that will fit in your door.
Tips and warnings
- Depending on your style of door, it may also be necessary to take off the face plates on the front and back of the door, surrounding the doorknobs. Do not do this unless you have to. If you have to, the screws that secure it should be located easily on the face.