bought possibly the only tube color Capeheart in private hands

[Electronic M]

So I have went over every capacitor and resistor in the horizontal and haven't found anything wrong. Last night it randomly started producing 18-20KV with the HV reg biased hard into cutoff and the CRT dark. When the HV reg is set up to conduct per manual and or the screen is bright HV slumps down to somewhere in the 10-16KV range and varies with picture content.

What's weird is I have full deflection, good drive, 135mA cathode current (supposedly the tube is rated for 170mA normal max opperation, but Sam's doesn't give any value for it), the flyback doesn't run hot, the HV winding resistance is reasonable, focus is measuring reasonable, but HV can't source current without slumping.

The only thing out of the ordinary I can find is R140 the 4.7k 1W that feeds the horizontal yoke center tap drifted up to 6.8K with discoloration and the new 2W 4.7K I replaced it with gets hot enough to sizzle water. I borrowed the yoke from my CTC-4 and cobbled an adapter for it and the HV was worse with the CTC-4 yoke but opening the center tap wire made it work about the same as the Capeheart yoke.
Not sure what to do next to try to fix this. Part of me wonders if moving the H OUT plate and focus rect plate to tap T on the flyback would help, I'm also thinking about trying it with the Capeheart yoke with the R140 lead unplugged.

I have a solid state 3A3 in it that doesn't change the HV level compared to the tube. Part of me wonders if there could be an HV filament winding current leak that I can't hear that somehow draws just enough to load the fly down to 16KV...I've been thinking about taking an HV socket cup from a junk set and a spare 30KV Doorknob cap and seeing how much HV makes without the stock HV rect filament wiring in place.


I was able to get the tuner to tune RF channels (it needs a cleaning bad though), and it is demodulation color though the chroma osc seems to not sync.