time to trouble shoot.
1st thing is to inject a composite video signal at the control grid of the video out. Looks like a reversed image on the CRT.
See if that works. FYI I had a set that did the exact same thing, (weak reversed pic) it was the result of a cap installed by the PO as part of a mass shot gun recap, where one lead was attached to the wrong terminal of a term strip.
https://www.youtube.com/watch?v=qkJ3yp0c2v4