Usually when the channels stop switching the LDR or Switching relay would be my first guess with already checking tubes. If the volume is there when R1 is engaged but very low, It would be my diagnosis the tone caps and or The large orange Sprague capacitors are suffering from DC voltage leak...
Hello, I'm restoring a 60/100 purple stripe 4-6l6gc tubes and I cannot find the stock screen resistor values for the power section. I have 4- 470ohm
resistors that I know are correct, but the others are 2.21k and does not seem correct. I measured them and they are in tolerance. Everything else...