Our Panasonic dimension4 NN-C2000W microwave sparked and made some sad noises. An unexpected piece of metal was in he bowl. Afterwards the microwave didn’t make the same familiar noises.
Upon taking off the cover to the microwave generator, the board had burn marks (carbon) that was now causing the microwave energy to bounce back to the generator, instead of out into the food.
A quick search on eBay found:
http://www.ebay.com.au/itm/361450471166 Universal Microwave Oven Mica Wave Guide WAVEGUIDE Cover Sheet Plates 3 Sizes.
$2.50 inc Postage, direct from Hong Kong.
Screwed the new cover over the hole and we now have a working microwave:
Total Cost $2.50 + 15 minutes time.