After looking up on the computer a schematic of the unit, all that was needed was removing four screws to remove the top and side cover which was one piece. Next was removal of electrical connection to burned out lamp, then removing burned out lamp and installing the new lamp and reconnecting electrical connection. Job was complete after reinstalling the cover.
Microwave now working with new lamp lighting when in use.
Door microswith was stuck on. This is caused, I discovered, by frequently stopping the oven, while running, by opening the door rather than using the stop button. Causes the switch to arc and eventually fail. This causes the safety microswitch to trip the breaker when door is opened. There are little nubs sticking up on the spade connectors. You must squeeze them down before you can remove them from the switch. The main door switch is the upper one, mounted at an angle. You have to remove the latch assembly to remove the switch. The problem was obvious once I got the switch out. This problem could also blow the fuse, but in my case the breaker tripped first. Use an ohmmeter to check switch and fuse. The door switch is normally open. The safety switch is normally CLOSED. Instructions inside were helpful and described this problem. So, avoid this repair by always stopping oven with stop button!
I happen to have a set of "security" screw driver tips which are required for this appliance - available for about $10 at Home Depot or Harbor Freight. Remove three security screws from back of housing, lift up and aft to remove the cover. The light is on the left in a "snap in" mounting so use a flat blade screw driver to push back the retainer and lift out the old bulb then disconnect the two "push on" wires and install the new light. Total time about 10 minutes. The only issue is the requirement for a security driver set.
