Lock on sliding door not opening smooth

Question

Hello. Our sliding door's lock will not operate smoothly. When we put the key in, it takes a lot of jiggling before the lock unlatches. It is purely by chance that we can lock or unlock it. Is this the problem of the cylinder lock where the key goes in or the dual hook mortises lock? If the latter, which model does it look like the replacement part would be? Thank you for your help.

Eileen

User submitted photos of patio door hardware.

Tom · Accepted Answer

I'm not sure if it's the key cylinder or the mortise lock that's the problem. There's a good way to know for sure, though. First, remove the inside and outside handle from the door entirely and then try to manually throw the inside mortise lock with a screwdriver. If you still need to jiggly it to get it to work, then the mortise lock is the problem. If it works fine, however, then it's the key cylinder that's causing the issue. Let me know once you've done this and we can work from there!