Try St Charles Isuzu, Talk with Merlin. He's great and they have some of the best prices around and do not charge shipping.

Does the domelight not work with either door? Does it work when push on it with the doors closed?
The grounding switch is the long slider under the D shaped latch opposite of the hinges. Make sure that the contacts are not corroded there.
You may need to get a circiut tester (The kind that looks like an icepick with a light bulb in it) to see if power is getting to the lights housing... No time like the present to learn The POWER of ELECTRICITY!