This MusiciansFriend bass is a great buy except that it needed set up upon arrival and it has a buzz thru the amp when pickup selector switch is NOT CENTERED in the detant between the two pickups. The idea is to be able to mix the signal of the two as desired. However, in order to not have the buzz I just leave the selecter pot set at center. Any ideas on how I can remedy this bug? I've tried cleaning the pot.