Mortise Lock Cylinder Removal

Mortise cylinder locks are held in place by a set screw in die edge of the door. From my previous experience as a locksmith technicians, sometimes, it's hard to get at this set screw unless the door is open. If the set screw is to be removed, the cylinder can be unscrewed from the outside by using a pair of slip joint pliers. 

There is usually a thin ring between the cylinder and the door that can be easily pried off with a screwdriver that will give you a better hold on the cylinder. With the pliers, you will have to get a good grip on the cylinder and turn it counter clockwise. The cylinder will screw out and with a screwdriver you can access and push the latch bolt back. 

Unfortunately, removing the cylinder with this method will strip the threads, and a new cylinder would need to be installed. Sometimes if the crack in the door is wide enough, like many older doors designs, a small piece of spring steel can be used and bent on the right angle of approximately 1/8" on one end, and use it to loosen the retainer screw. This will prevent from the threads on the cylinder to be stripped.

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