Looks like video is dropping out. If the audio is OK I would look
at the video after the SND take off point. Check the CRT pins also for
bad solder. This is a great place for an analyst & scope.
On the resister watch for 'lytic caps on either end. If one opens
the other takes over & heats things up. Seen that a few times on RCA tin can
19" colors. You could also pull the audio out, if in // filaments to see if things
cool down.
73 Zeno
LFOD !