The M80 is a legendary amp. World-class even. Unless it is trashed, it is well worth someone repairing it. Where are you located that you have no electronics repair services? This is not a tough fix for most any repair service if it’s just simply a bad cap or resistor or something like that.
Yamaha M80 Amp
I recently acquired a Yamaha M80 amp on trade for a bunch of equipment I needed to part with. It was in good working order but now, the right channel has died. The only repair facility reasonably close to me closed its doors several years ago.
Suggestions? Too darn heavy to ship (at reasonable cost) but not sure I'd want to take it to a recycling center. I don't feel I really need the amp at this point. I purchased (don't laugh. fit my budget) an Emotiva PT2 pre and A2 amp. They play really nice with my KEFs.