So... my mom has this around 30 year old microwaveoven. She loves it. Every time she forgets her coffee somewhere or just mix the rest together. Then she can nuke it for 30-60 seconds and have another sip. Her turning 79 this summer and still taking care of most things alone, there was just something right about fixing it, rather than replacing it. Me growing up with not that much, have given me a big satisfaction in repairing stuff - if possible.
The flat wire from the start button - that she has maybe now pushed a million times - broke somewhere. So I made a "jump-starter". It could have used a small cap to smooth operation. But I changed those in the power supply instead.... they needed it more
I lifted up the old soft touch panel, then drilled a hole through the plastic. Then ground down the rear plastic, until the little switch - that I dug out from a remote controlled lamp - fitted just so you can use the panel like before, but you simply push the switch behind the old sticky soft touch panel. Cutting away parts of the old flat cable, made room for a couple of wires. Then soldering with a huge iron that I found somewhere in my dads stuff, as I was cleaning out after he went to a nursing home last year, as part of his last journey.
Again - it seems like it's still mostly capacitors and mechanical stuff, that wears out.
It's not pretty - but it works, and she loves it even more now