I may have an idea about the stripped screw. There is an epoxy that they sell at home improvement stores( can't remember the name) that comes in two "sticks" to activate the epoxy you take a little of each stick (just enough to fill the hole) and mash them together. when they are mixed just stuff into the hole and then screw the screw in while it is still moist. Let it set overnight before trying to use the strap lock.
Hope this helps.
Spirit

P.S. I'm not sure about guitars but stuffing pieces of wood or other foriegn objects into the hole can definately crack window and door frames. Found that out first hand. :(