OK. Back for help now.
I deleted the OP 'cause I did not go thru the regular troubleshooting steps first.
So, here's what I got. A low left channel output. This is what I did:
Cleaned all switches and pots.
Took the plug-in boards out, and cleaned the finger contacts.
Took the Pre/Amp jumpers off and cleaned each and the RCA's on the amp.
Looked for a poor or cold solder joint. Found none.
Checked for bad caps or resistors. Everything looks OK.
Someone has been into this. 1 transistor has been changed. I'll assume the other 3 (RCA's) are original. They are all #2N3055's, but the replacement has no name on it. It has a square box with a S (?) or 5 (?) on the lid, then the part number. Anybody know the brand? A google search got nothing.
I also noticed that the replacement has a ceramic wire wound resistor (about 2inches long) from 1 leg to the other transistor's leg. Plus, there's white heatsink grease behind the insulator (?) on both.
The other side with the 2, has (what looks like to me) a carbon that is much smaller. No grease on those. Just the insulator.
Should I be looking to replace the transistors (all?) with new, or do you guys think it's something else? BTW, I removed the Pre/amp jumpers and went straight into the amp with another Pre I have. Same results. Left side low.
Any guidance would be appreciated.
Thanks.