A couple of my set screws are stripped and stuck into place. Possibly rusted or lock tited into place. Some knobs have a flat head screw, and some have an Allen wrench hole w/ a flat head screw on the opposite side. All of them are slowly coming off and every once in a while they rip off completely. My bedroom one I have to gently rotate to the right until it catches and it will open. Hope this provides some details. Any ideas?