Hello all. I just picked up a 1988 Sabre bass and I love it. Its a June/July manufacture white with a 3 ply black pickguard and birdseye maple neck. I'm contemplating a pickguard change to tortoise shell to spice it up a little. I hope someone here can help me with a wiring problem. When I turn the treble up I have a ground buzz that will go away when I touch the control plate, any of the knobs or the input cable (metal part). It does not go away if I touch the bridge or the strings. I've looked for a loose wire but all the solder joints seem to be intact. I've tried it with different cables and different amps plugged in different circuits all with the same results. Any suggestions?