I now have THREE, count 'em: THREE amps (1968 Fender Bassman, 1979 Park 1207, 2004 Soldano Avenger) that don't work and have the exact same problem (low-to-non-existent output). It is HIGHLY suspicious that all three amps would have the EXACT same problem at the same time. I've tried running through different speaker cabinets, I've tried switching pre-amp tubes, I've tried switching IEC cables, I've tried switching speaker cables, I've tried switching instrument cables, I've tried switching fuses, I've tried switching outlets. Is the power in my house killing the amps? That's the only thing I can think of.