Are these things I should consider bad

[N2IXK]

It is really difficult to follow what is going on with the schematic incomplete and in a different thread.

Can you post a bigger chunk, so we see where the ABL signal from the pot wiper goes? Somewhere into the video amps, I assume.

Scope the B+ voltage that feeds the video amps, and look for ripple/ringing there.

Check the zener diode using the diode check on a DMM as a first go. That will conclusively check for opens/shorts. I'm betting it is still good though. Im thinking you might have a bad bypass cap in the video amp somewhere.