I finally got around to taking the whole chassis and tuner out of the tv. Cleaned up the wooden cabinet. Checked all the diodes on the tv, all diodes tested good. I am now recapping all the capacitors that are known to be bad. Mostly the bad ones were small low value electrolytic ones on the pcb board. A bit annoying to get into the tight spaces on the board. I much prefer working with point to point wiring.
Flyback seems to test ok based on measured ohm values via a multimeter and comparing to the schematic. Will be cleaning up the high voltage cup more thoroughly this time to make sure no carbon tracing happens, if necessary a Dremel will be used.
Replacing a burnt out 6.3Volt incandescent bulb that illuminates the tuner.
In summary:
Flyback good, capacitors that tested bad are being recapped to rule those out, diodes all tested good, CRT is in great shape, and cleaning the HV cup again in hopes of stopping the arcing that keeps happening within seconds of powering on the tv.
Replacing a burnt out 6.3Volt incandescent bulb that illuminates the tuner.
Also, I now have a NOS vintage RCA high voltage probe, so I can now test what actual voltage is coming to the CRT. A bit nervous using this as I have never done so before.
Question:
Is it possible that the sole/original cause of the arcing was a bad doubler or tripler? There is a white box on the back of the high voltage cage that is believe is a doubler or tripler. Also perhaps the voltage is set too high on the potentiometer that sets it?
A theory I had was that as the emissions performance from the old Horizontal tube had declined, the knob that upped the voltage output was turned up to compensate...until the horizontal tube finally had failed and went to air. Now with the new horizontal tube in it the voltage is too high at current setting.
https://imgur.com/a/Wqq1s8l