Hello, I own both a standard Jazz bass, and a Music Man SUB bass. The problem I'm having is that the higher frets are out of tune with the lower frets, and so the 12th fret is out of tune with the open string, and the seventh fret is out of tune with the open string below it. For example: Let's say I have the open D string tuned perfectly, but when I play a G on the 5th fret, it is always flat, such is the case with all the other strings. But the worst part is the from the 12th fret up. I've had this problem for quite some time, and I am desperate for help.