I know the TB folks really encourage the search function, but I don't even know how to put it into searchable words. All I come up with is ground hum. But I've got the kind of hum that goes away if I hold my bass juuuust right in proportion to my amp. When it is in position it's dead silent, and I've already lined the beasty with copper tape. I don't have any ground issues. But how do I solve this perfect placement hum issue? It's a 70's Epi ET-280 with original pickups. Are my pickups just worn and tired? Are there any fixes other than finding the perfect place to stand at each gig?