I'm new to this group. I'm a BS EE who's serviced electronic equipment most of his life, so don't hesitate to get as technical as you like.
When I reviewed the NAD MR-20 for Stereophile 20+ years ago, I was so impressed I bought one. It's given me yeoman service; I suspect it has 20K hours on it. Until now, the only problem was some bad electrolytics on the video driver board.
The current problem is intermittent loss of brightness accompanied by loss of focus. Adjusting the Screen and Focus controls improved things, and removing the back greatly reduced the frequency of the problem (presumably because the set runs cooler).
This might be the CRT, but I suspect it's the HV rectifier. (Tapping the neck of the CRT has no effect, but that's not a definitive test.)
The problem is that the HV rectifier appears to be potted within the flyback transformer assembly. The transformer is no longer available (nor is the CRT). Before I yank the transformer (it's not easily removed), I need to know whether the HV rectifier is accessible. And, of course, I'd appreciate _any_ thoughts on servicing this set.
Thanks in advance.