O.K., I've been going through this amp for about 2 weeks now and it is making me nuts. I replaced all the electrolytics and did a blackface conversion and I think that helped the tone . I also removed the MV and put a PPIMV in there. The remaining issue with the tone is this kind of buzz overtone over loud signals,clean or dirty. I changed the tubes, cleaned up some ground wires (what a rats nest!) Nothing. I can't even seem to make it worse. I can tell the amp would sound great if I could get rid of this and I really want to figure this out, but at this point, I'm starting to look longingly at my Superbass on a chair waiting patiently for me. I read G. Weber's book to try and understand Fenders. The only posslble thing that I can find to try is increasing the swamp resistors on the OTs (they are 1.5K). Will this help. Man, I just want this to end ! Please help!