Not recommending this for obvious safety reasons, but I have brought
several
'dead' micros back to life by taking them apart and putting them back
together, cleaning all the contacts and microswitches I come across, and
replacing any popped internal fuses and melted connectors.

Likewise here. Still puzzled, but all I replaced was the lightbulb that
stopped working along with the rest of the uWave oven. This was a '70's
heavy box that still works.

Over the stove uWave ovens are not cheap - have you looked lately. So if
it's relatively new, may be worth trucking it to a service place.

If you can't fix it cheaply - give up on the over the stove type. Way too
expensive. Replace it with an exhaust hood and get a countertop model.
You'll have beer moeny left over.

Mostly I still use my 25 year old el-cheapo-at-the-time Korean
countertop micro with the mechanical controls.

Any basic applience should be bought with the most basic conrols. It's
cheaper and will last longer. Also have a chance to fix it yourself/

RichK