Adcom GFA 5300 schematics and advice please

I have a GFA 5300 that had a bad bridge rectifier a while back and I recently tested it before selling it and found a channel that became distorted at high volume ( happens to be the one with the new Bridge rectifier) Sounds like a torn speaker and when I put a scope on that channel I see what looks like high frequency oscillations on the peaks of the signal when I have the volume cranked up Looking for Schematics or any suggestions on what to look for The DC out from the power supplies looks the same for both channels so I don't think its the rectifiers but you never know I did notice that this unit was reworked and heavy buss wires were attached where the copper foil was obviously too light to carry the current Thanks in Advance Bob.