From your video, and the replies in this topic, there appears to be neck glow, or what could be a short in the neck visible around the 0:10 sec mark in the video.
Going over what you posted, you may have gotten lied to by the original owner. "Yeah it was working fine then it suddenly turned off".
If i sell you a lightbulb which 'was working fine but suddenly turned off'.. well you get the idea. (Something is always working fine until it breaks.)
I would cut my losses at this point. You're going to end up spending a lot of time which equals money trying to get this going.
Plenty of options for crt's in Naomi/nnc. MS8, MS9, 29E31, Sanwa PFX, and so on. From my own experience, i try to stay away from 29E31 / Shanghai novel tubes
MS8/MS9 with the right bezel will be a great combo for a Jaomi.