Don't know if this was covered already, I searched didn't find anything specific.
I'm sure there are others in the same boat as I am, needing repair of their prized old amplifiers. I got an e-mail back from DB-r electronics and they said they don't work on old equipment, and they recommended I contact Zedaudio.
I have a tech that I go to locally that mainly specializes in really old equipment, 50's & 60's tv's, home stereo equipment, he used to work for a Sony repair facility and repaired radio station transmitting equipment, and he also does state of the art video editing equipment, he's very good and reasonable, to me at least.
Right now he has a Aiwa cassette deck that I know he's ready to throw across the room, LOL. I spoke to him today and he told me to bring my amp to him and he would look at it. We'll see if he see's something obvious.
But any other shops that people here have used and can recommend? I know about United Radio in upstate NY, they worked on a few of my head units way back but they don't work on anything that the company is not in business, makes getting parts difficult.
Also does anyone have any service manuals or schematics they would like to share, possibly a new section could be created for them.