A relative got locked out of a rental house (out of state landlord) due to a balky mortise lock in a decorative metal frame outer door. He called a locksmith to get him back in and the locksmith installed a used but "working" mortise lock which was still unreliable. I was over at his house and was asked to and agreed to "look" at it. At this point I am profoundly regretful that I became involved, but at the least must restore the lock to what it was when I unwisely began working on it.
I had never installed or replaced a mortise lock and blundered. I unscrewed the outer deadbolt cylinder and couldn't get it back in. I think the threads on the lock body and the deadbolt may be damaged. In trying to back out the outer deadbolt which I had cross-threaded trying to get it back in, I broke off an aluminum key in the cylinder. Right now the door works from the inside, but has the deadbolt missing from the outside.
My immediate question is can I remove the broken off part of key from the cylinder or is that part ruined? (I have access to the back side.) If I can get a new deadbolt, how does one screw it in while getting the actuating tab that operates the deadbolt in the right place to function? Is there a tool like a thin wrench that allows threading in the deadbolt actuator while holding the key to keep the tab in place?