1998 Plymouth Voyager Parking /Running Lights Not Working -

We are having a problem since 2006 with our Voyager on and off. Took it to the dealer to look at our parking / running lights not working and the dash not illuminating when the headlights are on. By the time we got it there, everything was working again. They didn't find anything. In 2007 we again had the problem, and they replaced a headlight switch. Again, the problem went away till this year, when it came back. They suggested replacing the switch, and since parts were hard to come by, we bought a used switch and had it installed. Worked 2 days and now we are back where we started. Headlights work, dash works and the odometer stays on bright - but the guages are not illuminated and the parking / running lights are not on which makes it very dangerous to drive at night. What else could it be? This is frustrating as heck.