On Sun, 19 Jan 2020 13:39:12 -0800 (PST), John-Del
wrote:

Lots of circuit maladies will simulate a weak CRT. Start with voltage readings, move to waveforms. Low high voltage will cause the picture to dim as the drive to the tube is increased for instance.

I was given to understand elsewhere (which is why I'm double-checking
here) that a CRT which has gone dim and reaches its peak brightness
before dimming again towards the end of the intensity control sweep is
irretrievably ****ed and not worth further investment in time. It
would be nice if that advice is indeed incorrect!

--

No deal? No problem! :-D