I have an old cheap p-bass knockoff that i want to set up to be able to play. the neck has huge amounts of relief and i want to straighten it, but the truss rod nut won't tighten any further. i pulled the nut all the way out, and it looked fine, and went back in without any problem, so i don't think there are any problems with the nut or the rod. the only thing i can think may be wrong, is that the nut is tightening all the way, and can't go any further. it's an allen key nut. what i need to know is wether or not i can add a washer or two under the nut to give it more movement. will i be doing something that will hurt the bass? i think this will fix the problem, but i don't know for sure. has anyone else tried this?