Sanyo DCA 600 distortion

The right channel on my Sanyo DCA 611 integrated amp is distorting on higher frequencies. It happens on headphones and speakers. When I switch the L+R selector to reverse, the problem goes over to the left channel. There's been fuzz/static in the right channel for a long time when adjusting the volume, until I do it enough times that it goes away, but this distortion issue has gotten worse as of late.

This must be a fairly common issue among devices of this vintage. Any suggestions? Thanks.

Get a service manual, read it thoroughly, sometimes they have troubleshooting procedures, find some test equipment(DMM) and start to troubleshoot by first measuring the power supply voltages.
There could be many possible causes, some maybe specific to your make/model.
I can not find a SM, so it is hard for me to help you any further, other than in general terms.

I managed to find a service manual online, but unfortunately there aren't any troubleshooting tips. The fact that the problem follows a channel when switched would indicate to me a certain paired component is the problem. The only thing I haven't tried yet is a different input, which I'll try tonight.

Assuming it's not the input, and knowing that the distortion occurs on headphones and speakers, it seems like the problem would be a paired amplifier component.

I'm looking at the schematic but it's tough to figure out the pathways.

My extremely limited electronics abilities have led me to believe the problem may be either a 2SC1571 (G,H) or a 2SA798 F transistor. There are two of the 2SC per channel, one of the 2SA.

In a situation like this, is it more likely to be a component failure rather than a connection?

Or is the distortion simply related to the fuzzy/static I get in the right channel when adjusting the volume? Could it be something as simple as dirty pot?