I'm thinking of buying this Admiral

[Phil Nelson]

Originally Posted by MadMan

(I think) an adjustable electromagnetic focus ring?

Sounds like an ion trap magnet, if it's an adjustable circular gizmo around the CRT neck. You can read about that and many other wonderful details in the Rider and Sams service manuals available at the ETF archive (scroll down to 20Y1):

http://www.earlytelevision.org/tv_sc...s_admiral.html

Originally Posted by MadMan

do you think I could get away with just replacing the filter caps and making sure all the tubes are ok, in order to see if the crt will give me something? You know, before I go all the way and recap the whole thing?

Sure, that's one approach. If your CRT is truly a dud, you still might not see anything, but at least you could measure key voltages and compare to the service manual values, and discover other things depending on what test equipment you have.

Also, as mrjukebox160 notes, some CRTs that look dead at first will "wake up" and show higher emission if you leave them on the tester for a while.

Phil Nelson
Phil's Old Radios
https://antiqueradio.org/index.html