Finding the problem was exacerbated by the unique fasteners holding the cover to the guts of the microwave. Once apart using the schematic diagram the problem was located and found to be a failure of one of the three safety switches on the door closure part of the chassis.
The failure extends to the plastic holder of the primary switch, so the holder and one replacement switch were ordered. Appliance Parts Pros had the parts in stock and promptly shipped them. They are all exact replacement parts. The cost of parts was reasonable and much, much less than a repair call!!
Appliance Parts Pros is the place to purchase appliance parts for any DIY repair.
Thank you all