Mostly what goes bad from disuse of these things is the power converter boards, and there, it's the capacitors. BUT.
I have seen video of someone using a variable AC power supply to slowly bring power up on such a vintage monitor, thereby reconditioning the capacitors. Or so I presume that's what they were doing; they didn't explain it.
Building one of those is expensive, but old-style dimmer switches (and other variable resistors) aren't, so much. Particularly since I already have them.
For, oh, two-time usage, can I just put that in-line with the AC power and do something akin to the same thing? Or would this approach damage other components?
(The NEC Multisync (original) and Multisync II (1988), both of which worked when last turned on (some 10+ years ago) died almost instantly after being turned on. am 90%+ sure that the quick death was due to high voltage power supply board capacitors, and the LCM wanted them anyway, probably just for the CRTs themselves but the original's case is in good shape so maybe for that too, so that's fine.)