I just bought a used Fender Marcus Miller Bass without hearing it (no electricity-swap meet). Everything looks great and all original parts but I need help because when I took it home and plugged it in, it hums (60cycle) like crazy. Do I need to buy some shielding or give up and buy new noiseless NLS pickups. It stop humming as long as I keep my hands on the strings or control knobs. I'm bummed, it looked like a great deal. Your expert advice is greatly appreciated.