[RodB]

Looking at the schematic you'll see a dashed line starting with the power switch running to the right to the tone control circuit switch. The dashed line indicates the switches are physically linked to the same shaft. Examine it for small openings and spray contact cleaner into the switch. Then work the switch back and forth many times.

I also noticed the line filter is wired to the wrong side of the power switch. After replacing the line filter caps, move that connection in to the other side of the switch. Now the line filter will only have power when the switch is on. Make sense? I've seen several line filters blown apart because whenever the set is plugged in there's power on the caps.