Doorknob Capacitor advice needed

[ohohyodafarted]

I have finally finished rebuilding the chassis for the Midwest Radio and Television set, and was able to power it up on my variac last night.

I had to install a complete compliment of tubes as the set had none when I got it and after running down some issues due to marginal tubes I got a raster and video. Set looks like it will have a nice picture once I am able to narrow down this High Voltage issue.

At first I thought the flyback was taking a dump. I could hear arcing but could not see any corona or sparks. AS I increased the line voltage to 118, the arcing got more pronounced. I took the HV cage off and used a 2 foot peice of vinyl tubing with one end stuck in my ear and the other end as a sound sniffer to narrow down the location of the arcing sound. Much to my surprise it is comming from the bottom end of the doorknob caps. It appears they are breaking down internally because I cant see any arcing from them in total darkness.

One doorknob is from ground to the CRT HV lead, the other is from the filiment of the 1b3 to the plate of the damper. There is a 1meg resistor from the junction of the HV lead/doorknob, to the 1b3 filiment side of the second doorknob. When I approach 120vac on the variac, the 1meg resistor will start to smoke.

I removed the doorknob that goes from the HV lead to ground and that eliminates the arcing sound, but I get lots of corona generating ozone. Is it likely that the grounded doorknob is breaking down, even if I can't see the sparks that I hear?

Does anyone here have experience with bad doorknobs? If you could describe the typical symptoms that would be appreciated. If they are arcing internally can you still hear the sparks?

I don't have any doorknobs to sub or I would try that.

Thanks,
Bob