O-scope giving problems

[Ed G.]

I was given an old Tektronix T922R oscilloscope a while back and recently I can't get the trace to show on the CRT. The CRT is good, and I get something on the screen when I hit the "beam find" button, but the trace won't show.
A few days ago, the trace showed up after about 5 minutes. The next day it lit up right away. Now I don't see it at all. I'm thinking some aging electrolytic capacitors, but I'm not sure.
I found this site: http://www.logwell.com/tech/oscilloscopes/T922R_service_notes.html

Which states this:
"U4134 and U4234, CA3086 / LM3086 devices, are prone to failure, causing the trace to go full high or full low with location only possible using the "Beam Find" button."
Think this might be the problem?

[Paul Perry (Frostwave)]

There are two different possible problems:
1, a 'deflection' problem, wher the beam generatign electronics are OK but the beam is permanently too high or too low (but, the finder can get it).

2, a EHT power supply or modulation problem, where there is either no beam at all, or the beam is (for some reason) switched off all the time.

When the beam 'appeared after five minutes', did it slowly appear in the right position,or did it drift onto the screen from above or below?