Look for the FA board. If not mistaken, this has the 6CW5 vertical output tube on it, and the horizontal oscillator tube. 6CW5's can cause lots of issues.
I have not seen one of these sets in at least 20 years.
If not mistaken, you need to remove that 1/4" hex screw near the power connector before you pull the drawer out the front of the set. I can see it in your pics.