Picked up a B52 AT100 triple Rec tube head. Great deal, but it sounded pretty scratchy. Thinking new tubes and a tuneup. Anybody know anything about these amps? Best place for repair/tuneup? I see lots of recommendations in last post too. Scooter Barnes? Enrique Jimenez? Jamie Hillyer/Brettonius Dutchmaximus Seyfarthius...you guys familiar with these?