Kenmore Microwave Oven 99421 Repair

Sears Kenmore Microwave Oven 99421: Manufactured in 1981.
Problem: Slow fan. Hot and cold areas with uneven cooking.
Modern microwave ovens use a rotating plate to even out the heating and prevent hot and cold areas. In this early microwave, a "stirrer" was used. A stirrer is a metal disk with microwave reflectors. It was hidden under a plastic sheet in the roof of the microwave cavity. The disk must spin in order to break up the microwave standing wave pattern. The microwaves are generated by a magnitron. A fan is used to cool the magnitron. That airflow is also used to drive the stirrer. In this microwave over, the fan could take over a minute to spin fast enough to generate air flow strong enough to spin the stirrer. As a result, there were hot and cold areas and cooking was uneven.
In this video: The microwave oven is opened. The fan is removed and disassembled. The fan is lubricated and put back in. After lubrication, the fan spins up to full speed immediately.

[@mraiwa1000]

Very informative and well-done video! Glad it was relatively simple to get working again.
P.S. would be neat to see a video of that retro dishwasher too!

[@SamBreitenbach-ej7cb]

Medium power level means the magnetron operates 50% of the time and defrost means the magnetron operates 30% of the time