1997 Sundancer 270 7.4 Gauges won't illuminate

Hello,
For some reason the gauges on my Sundancer don't come on with the nav lights.
I fiddled with the dimmer switch - nothing. Can't see any breakers tripped and I checked them all. Nav/anchor lights and switch work just fine.
Any ideas on where else to look and what else to check? Gauges work just fine.

I would get a volt meter and start checking the light switch and the dimmer switch to see if it's even functioning.