Like Jim's, our GE micro/convection interior light has blown twice. First time, GE came out to the RV. I contacted service online and they gave me a call to verify "which light" was out before they arrived.
Second time the light went out, I ordered 2 bulbs from GE website and David replaced it. We still have 1 as a spare.
Website has diagrams and part #'s. You can also register the oven if you haven't done so!
http://www.geappliances.com/