My Dumont was wrapped with a plastic cone of insulation too, but the metal to glass weld was visible at the neck, and that is where the 2" spark came from to hit my hand. Like the cat that jumped on the hot stove, I decided not to trust that set again, hot or cold.
Don

Very soon after transistors came to TV sets, gap-caps, neon lights, and other devices
started to appear because CRT's let go with a spark, internal or external occasionally.

This had no effect on tube circuitry.

Especially those fresh out of the box, color CRTs from the cheapie rebuilders... Some looked like a 4th of July party was happening in the neck when the HV first came up... Weren't so bad if the cathode was hot when the set was powered up, but in solid state sets that meant lighting the tube with the CRT tester or external transformer just before turning the set on...

Tom