I have an NEC MS75 CRT monitor that's 3 or 4 years old. Lately there
have been times when the horizontal sweep shrinks slightly, for less
than a second. It can happen every couple of minutes or not happen for
several hours.

I seem to recall something similar with my last monitor before it
suddenly failed. There's a relay that clicks when I change resolutions
or put the computer to sleep. I suspect this relay because I do these
things much more than other computer users I know. I have found reports
online that with other monitors this relay has been associated with
narrowing of the display.

What is the function of this relay? NEC says it closes when you go to
800x600 or higher. That seems to be true; of my five available
resolutions, there are two transitions where the relay doesn't click.
However, it clicks twice when I go to or from 1024x768.

It clicks once when the monitor is put to sleep or waked. The screen
goes momentarily black any time I switch resolutions, whether or not the
relay clicks, so the relay doesn't cut power to the flyback.

Not understanding the function of the relay, I'm afraid it could cause a
sudden monitor failure.

This relay has an SA surrounded by a C.
It is labeled VBT12TBU-5.
1/6 HP 120 VAC
5A 24VDC.
0124L2.
How can I get a replacement?