21-CT-55 power supply failure

[miniman82]

Originally Posted by CT-100

The drive waveform asymmetry would be a place I’d start investigating.

Agreed. So I understand that the waveform applied to the tube is what develops the bias, but what could cause it to be too high? It's possible the high voltage doorknobs are getting leaky, causing HV to sag. I already repaired one that had fallen apart, but I'm not sure it's possible to get an exact replacement anymore.