[villagetinker]

To all,
Many of the original receptacles and switches use PUSH IN WIRE CONNECTIONS. Personally I do not like these. My step son moved into a mobile home recently, and in the process of adding a GFCI to bring it up to code, some of the wires in other receptacles on the same circuit pulled out of the receptacles as I was taking these out of the box, YIKES!!. I immediately replaced every switch and receptacle, and use the screw terminals.

A follow up discussion with UL indicated the specific brand (about 20 years old) was recalled and delisted due to problems with the push in connections, and the newer versions were redesigned to avoid these problems. IMHO, I still like the properly torqued screw connections.

I would hope some of the electrical inspectors jump in here.....

ALL, please do not attempt electrical repair, unless you really know what you are doing, plastic boxes are not going to contain a fire, and while the push in connectors are typically use, it is interesting that there appear to be more then one instance of problems. I will be inspecting ours tomorrow.

AJBrown, I would bet the black wire was nicked and stressed to the point of almost breaking, then repeated used (aka heating and cooling) caused the failure, this is just a guess.

Also, you could take the microwave to the garage, there is a dedicated 20 amp GFCI circuit, or use one of the counter outlets (15 amp GFCI) in the kitchen. MAKE SURE YOU HAVE A CUP OF WATER OR EQUAL IN THE MICROWAVE. But I would have the cord set carefully inspected for damage, and replaced if possible.