I run across a lot of loose screws, especially in locksets and door hinges. Even in cases that seem hopeless, epoxy glue can be used to provide better purchase for the threads.
First, I comb the screw through my hair to put a thin layer of oil on it. Then I poke some epoxy into the hole, daub some on the screw, and insert the screw into the hole. Once the epoxy sets up, the oil on the screw makes it easy to remove the screw if necessary.
Vern Wall, Phoenix, AZ
