Or Billington in the UK.You're restoring K&H UE100's?Jakob E.
The UE100 seems to be VERY forgiving when it comes to tube types. I would just get some halfway-decent types (maybe EI?), check that they actually work, put them in, and forget about it...Also, if you're restoring, it's far from unthinkable that most original tubes are still within specs..Jakob E.
Measure the DC Volts at the switch, both ways. You probably have a leaky coupling cap.