I have been working on this one for quite some time. Originally receiver had no sound from both channels. I didn't even try to investigate since F-1040-1 looked untouched and black squares had corroded green spots on their supports and on transistor bodies. My first round was replacement of outputs, all electrolytic capacitors on F-1040-1 boards along with TR 803 and TR804. Replaced black square "Origin" temp compensators with NTE-605a pairs. Cleaned all controls and Adjusted Bias and output voltage. I was exited to have sound through headphones, but as soon as speakers were connected, sound was distorted through both, speakers and headphones. Scope clearly shown DC in output. Replaced all 4 cans with 3300 @ 100v Nichicons, replaced all 8 in diode stack and rebuilt protector board (diodes, zeners, e-caps). Re-adjusted amplifier boards and fired it up. Great sound at normal to higher volumes. Low volume is another story. Sound is distorted and jittery almost like bad cell phone communication. It breaks through with audio signal peaks and gradually goes away as volume is increased. No DC in scope pattern. Input signal from preamp is good too. Anyone ever seen this?