My panel gauge started working sort of. It doesn't start to read until the machine warms up but consistently comes back to life as the temperature begins to read. The fact that it starts and remains running lets me know it has oil pressure.
I still do monthly tests. I check all the fluids, look for leaks, and run it under a 40 amp load for an hour or so.
Last time I looked at the mechanical gauge was two months ago and it was still on par with the panel and no leaks. Pressure has stayed just above 20 PSIG hot since the last oil change.