Engineering question: Tube Camera Survivability

[ARC Tech-109]

I'd look at the tantalum capacitors (and electrolytics) in the magnetic focus and deflection circuits. I had a DXC-M3A for over 30 years and know they're electrostatic deflection system isn't the most robust, I highly doubt the mag focus coil has shorted as these are running at only a few volts.
One thing electronics from this era is known for is the little dabs of bonding glue the factory used to secure various parts to the boards and it's known to rot over time and become conductive. The HV supply on the top has a number of parts secured to the board using this glue and it's a really good ideal to get in there and clean it ALL off using whatever methods short of a heavy wire brush. I found acetone works best with this but regardless of how you remove it all traces must be removed and it will take some effort. The glue is also known to damage the green solder mask along the traces so do be careful and recover them with clear acrylic nail polish.
Pull the plug from the board for the green focus coil and swap it with another say the red or blue and note the change.