Hello. Today I picked up a used 1994 P-Bass. It is a white finish with white pickguard, which I don't care for. I was working off the knobs to change it when the glue on one of them came loose. The outer knob came off while the plastic remained on the pot. This means I cannot remove the knob and the pickguard. Has this happened to anyone else, and if so, is there a fix? Everything works fine, it's just the colors annoy me. Any fixes or advice would be appreciated.