Dave:

You are right on the relay operation - I should have caught that - and it makes sense that a power-drop would also drop output.

I will signal-trace, but given the symptoms, and with proper understanding of the relay operation, I am even more suspicious of the relay. Most of the caps are new (less than 10 years) and the switches, contacts and input jacks are clean. But, testing leads to better understanding - all good.

Thanks for your suggestions!

Peter Wieck
Melrose Park, PA