Thanks for the suggestion. There's a local A/V repair shop near here that I would consider giving a shot at repair (and/or improvement via mod) if there's insufficient info or a need for more sophisticated testing equipment than a multimeter.
OTOH, in hopes of a better alternative, given that Murrel owns some MFWs as well as performs A/V repairs, IMO he's in a good position to assess whether there's enough value in repairing these amps to justify a cost, depending on who's doing the labor.
Given this vested interest, if he says he's not interested in doing repairs b/c the cost (his time, our money) doesn't result in a reliable product, I won't bother taking an old one to a shop--local or elsewhere.
But if he comes back with "For amp version X with symptom Y replace Z" and you're able to obtain part Z and replace it (yourself or some other shop), I'd be interested in knowing that, too.
