I've got an old Squier J Bass. It's my beater. I haven't taken it apart and looked around yet, but just wanted to get a thread started on this. When the volume knobs for the pickups are at the same level, it sounds pretty good, no noise. However, if one pickup is turned up more than the other I get a buzz. Like I said, I haven't pulled the cover off to see if each pup is grounded, or is the cavity is even shielded. It sounds like a grounding issue to me. Anyone have thoughts?