Well, maybe the Subject line got your attention. I just wanted to
vent a little and warn others of this potential problem. My 2 year
old Whirlpool microwave oven started producing a burning plastic
type of smell. I didn't notice it at the time, but it was always
when we did a bag of popcorn. The oven has a "popcorn" button on
it, after all. Well, after a few weeks of sometimes smelling and
sometimes not, the turntable stopped rotating. I removed the glass
turntable and attempted to remove the plastic roller "spider" unit
and it wouldn't come out. After doing some Google searches, others
said it may not come up easily, so a little force in in order. I
pried with a large screwdriver and it come out with not too much
problem. However, hole in the bottom of the spider was definitely
burned. So I proceeded to remove the motor. After more Googling, I
found that Whirlpool put in a cover plate at the bottom of the oven
which must be cut out with side cutters. Replacement was easy as
you flip it 180 degrees, put the tabs in the slots and add a screw
at the other end. Cute design! I removed the motor and its shaft
end was also burned. The motor was rated at 30 volts AC, so I bench
tested it with 30 volts AC and it rotated fine. I called my
appliance parts guru and asked about the 2 parts, the motor and the
spider. He said, "Ah making popcorn?" Together they were about
$100. He said the bag transfers so much heat through the glass to
the spider and shaft causing it to melt down and burn. Nice,
Whirlpool, you put a popcorn button on a machine that will self
destruct if you try to use it to make popcorn. I managed to
moto-tool out the 1/2" diameter rotating plastic piece in the motor,
making a 1/4" flatted shaft hole. I then fabricated a 1/4" flatted
shaft from a piece of plastic and epoxied it in place. It was still
able to grip the flatted hole in the spider. All is fixed and
working now. When we do popcorn now, we put an old, I don't care if
it breaks, plate under the bag. The middle of the plate becomes too
hot to touch after just on bag. If this repair breaks, I'll
probably get a 1/4" nylon screw and form the shaft from that. Or, I
noticed on ebay, you can buy the exact oven for about $70 used ....
basically, a boatload of parts for future fixes. BTW, my previous
microwave oven, a built in GE, I think, never had this problem. It
made 100s of bags of popcorn in its life and is probably still going
strong in my previous house.

Also, Whirlpool WILL NOT SELL YOU THE PART due to "safety concerns".
Thanks again Whirlpool for being a great company. I know there
are many places on line where you can get the parts, albeit at a
premium price. But I'm sure, if you had factory service replace the
parts, they would cost the same or more.