Ok. I've removed the battery - have a new one on order. When reassembling I found that J2208 was installed backwards initially. Corrected but no change in behavior. All further testing is done with the battery removed:
These all seem to be in spec.
I have a 6kV probe on order - should be here in a few days. I will probe the HV line at that point.
Beam finder does nothing. There is no display at all - no text, no beam. No change whether the front panel is powered up or not.