Resurrecting this old thread since it's exactly the issue I'm having. I'm seeing the same artifact that's described here, and it's due to ripple from the HV oscillator that shows up on the Collector Sweep.
I had to replace the HV caps, C812, 813 & 818, as it wasn't getting anywhere near full voltage with the old disc caps. All of the paper caps test good up to 600V; they're not bumble-bees or black beauties, but newer red ones (dunno what you'd call them).
Are others experiencing the same thing?
thanks,
Paul
