Replacement is the best option.So, is there any way to clean these relays or is it a replacement? I have a similar problem with an NEC preamp. At low volume one channel can drop out, I crank up the volume and it comes back. It's all logic controls, no physical speaker selector or source switches on the front, just pushbuttons that scroll through the choices. This relay problem sounds like the culprit.
Sorry for the tangent, or maybe hopping onto your wagon is a more appropriate term.