Dust out the lock s case and spray it with a penetrating lubricant such as wd 40 as shown.
Replacing an old mortise door lock with a modern lock.
Once you ve removed the door lock template you have a space perfectly primed for your new lock.
If it s a tight fit try loosening the opening with a chisel to ensure the door doesn t split during the installation.
Remove the screws attaching the inside face plate to the edge of the door as well as the plates on the door faces.
Fit the new lock body into the old mortise.
Replace the cover and make sure the key throws the bolt from both sides.
Paint over the block to match the rest of the doorjamb.
If you want to switch to a cylindrical design typical modern knobset mechanism is housed in the knobs and a cross bore rather than in a mortise or a rim surface mount lock you ll either want to leave the old mortise lock in place or glue in a block cut to exactly fill the space it occupied since otherwise the empty space would weaken the door.
Reassemble and replace photo by kolin smith.
The problem with replacing the mortise with a bored cylindrical lock is that the new lock is smaller than the old and really has to be in the same location on the door as it s the strongest part of the door.
Use a screwdriver to remove all screws rather than a drill.
This can usually be done by removing a few screws in the door knobs around the face plate and the lockset.
Same issue exists regarding old holes in the door faces.
Start by removing the old hardware.
Then put your key in a nice safe place.
Reinstall the lock in the mortise screw on the faceplate and replace the spindle and knob.
Place two screws from your new door lock kit in the doorjamb to hold the template in place then use the bit from your lock installation kit to drill a hole where the new doorknob will go.
You d have to fill the mortise hole with a solid block of wood which might well entail digging out more of the door to get a good fit.
Pull the lock out of the edge of the door.
If you have questions please ask.