My blue line B15 died on me a few months ago (had been playing it, put the bass down for 5 minutes, and came back to an amp that had shut off and wouldn't turn back on). It's blowing fuses now upon powerup. I finally got around to taking it to a tech, who in attempting to diagnose it found mods done to the circuit from a previous owner, and he has told me that it's essentially unfixable, because the damage that was done with the mods make it impractical to fix. Though I don't have an electrical engineer bone in my body, I'm no stranger to having vintage amps repaired and I'm having trouble wrapping my head around this being possible. Is there something weird about the early 70s B15N's that makes them an especially tough circuit to work with? I can't imagine that every major component failed at once, so am I naive to think that the worst case scenario here is something like de-modding it and replacing a blown transformer?