I've spent far more time on this set than I ever expected trying to track down the excessive width issue.
Finally, as I was about to abandon all hope, I noticed the huge power resistor in the HV cage was cold! An ohmmter confirmed that it was open.
Now where to find a replacement ? Luckily, I have an entire space 30A1 parts chassis but it too was bad.
So, I pulled one from another of my Admiral sets,. Ugh! All three are bad

I'm guessing this was either a common point of failure back in the bad or they go bad just sitting idle over the years.
I have a coupe more sets to scavenge from otherwise I'll cobble something together.
Regardless, I'm going to have to find a source of replacement 5,300-6,300 ohm 50W resistors if I want to get all my sets working properly.
Note the taps are 500 ohms apart and used to correct horizontal linearity if needed. All my sets use the center tap so that would be 5,800 ohms.