[vcf-midatlantic] OT - Analog receiver occasionally missing a channel (but then OK for a long time)

[John Heritage]

I have a pair of Onkyo receivers that have different 'missing channel'
issues.

For "Receiver A" -- The behavior is I'll turn on the receiver,  and I'll
have 4.1 sound instead of 5.1 -- usually the right front channel is totally
missing.  No matter what I do, the only way to get it back is to power it
off and power it back on again, and then it's stable for a really long
time, including some future power off/on events.

Receiver B - which I "retired" a while ago (sitting on a shelf) - it had
similar behavior except if I cranked up the volume really loudly on the
missing channel, I'd hear some static and then it would work fine.  This
got worse over time - though once the initial sound output was working it
would always stay working.

Is this a sign of caps starting to go bad?   maybe discrete logic?   For
Receiver B I did take it apart once before and didn't see anything
immediately obvious to my eyes at the time.

FWIW The source is a 5.1 RCA analog output from a Soundblaster device.

Thanks!
john