Wes,
If you're watching this group and thread still, I found another disfunction that was confounding the trace:
The vertical amp input, Q4402, was dead, and caused the vertical plates to be stuck high. So the trace would only show up if BEAM FIND was half pressed.
After pulling the transistor out I found that the passivation in the can was only half filled. So it was just a bad part that must have failed at some point not being sealed.
It also appears at least one tunnel diode is dead. I used some 2N3904s in place of Q4402/Q4412 for testing, and I'm able to get a waveform, but only with the trigger holdoff tuned just right.
I have parts in hand and on the way. I'm going to have fun fixing all the issues this scope has, but it's pretty funny that there's just about nothing on this scope that hasn't suffered a failure in some way. It'll be fun to rehab it to full working condition again. It's going to take a while.
Dave
Dave Peterson