How to replace halogen bulb in GE spacemaker microwave? ?

How do I replace halogen light bulb in My GE Spacemeaker Microwave?
I have a GE Spacemaker Microwave Model JVM3670BF 07.
This model has a venting door across the top that opens to release moisture when heating food. This is not a grill, so there are no two screws at the top of this which will let me remove it to access the light bulb housing,
The manual that came with this treats this part as a grill, but does not cover the model with a self-opening vent. Calls to GW for tech assistance resulted in otal frustration and an admission that "we have no tech advice for you."
Can someone help me with this model?

Thanks.

JB BARINHOLTZ
April 2010