Help. dead channel on GFA 555.

I accidentally hooked up my old GFA 555 to my speakers with the mono switch engaged, this blew the right channel. my local shop repaired it twice and every time i get it back up to about 50 or 60 watts (guessing) the right channel goes out. i mailed it to "Inhouse Service Center in Seckaket, NY" . What are some educated guesses at what I did and what it needs now. It is a gfa 555 series 1 from about 1989. Which i purchased new and has never given me any problems. thks chuck

ps- while they have it opened up should i ask them to replace anything else to improve its sound?
Re: Help anyone?

chucker said:
i cant be the only one in the world with this problem can I? thks chuck
The service clowns are probably buying counterfeit transistors for replacements...knowingly or unknowingly. The original outputs should be replaced with On-Semi MJ21193G and MJ21194G, purchased from a reliable source, such as Newark or Digikey.
ZigmundRat said:
Sorry I can't help with suggestions on your problem, but I too have a GFA-555 with problems. Does anyone have the full service manual in PDF they can send me? With this popping the main fuse every time it's turned on, I think I'll need it :) TIA.
Adcom still enforces copyright on their manuals. Call them, they'll sell one to you.