Sorry if this question has been asked before (I dont think it has) but I tried adjusting my truss rod recently and wasn't able to do it. I stuck the Allen wrench in the hole by the top of the neck of my bass (Fender P bass), but when I turned the Allen wrench, nothing changed. I tried several different sizes of Allen wrenches, but I couldn't feel any resistance while turning any of them. Is it possible that the hole has been stripped and the truss rod is now impossible to adjust? I got my bass used so I suppose that might be the case. But it's more likely that I'm just doing something wrong. Can someone explain exactly how to adjust the truss rod? I would be very grateful.