It works again!!! (50-year-old GE microwave oven)
The past decade has been a bit busy and stressful for me, so when, maybe 7 years ago, my vintage 1976 GE microwave oven stopped working, I replaced it with one I immediately picked up at a garage sale. That one I also had to replace some years later, and I may have even replaced it again, since.
So when the current incarnation crapped out on me -- rather obviously, "ZAPF!!!" -- I crept on down to the basement to check whether I had any microwave there that actually worked. (You didn't think I'd actually thrown these things away, did you?!) The second one I plugged in was the one I bought at Sears in about 1976 (a 1975 model on close-out sale, IIRC). I plugged it in and it came alive! So I put a small glass jar of water into it and gave it a half a minute or so -- and it got warm. Cut to the chase, I now have that 50-year-old microwave oven back in my kitchen, working well, apparently.
Cast your mind back to appliances of 1976: No mother board. No clock. No digital display or any display at all for that matter. The timer is mechanical -- like the heat-lamp timers in motel bathrooms. But it works! I don't know how long it will keep working -- it did seem to die some years back -- but it's working now. I'm sipping ginger tea I just made from a mug of water I heated in the thing. I'm tickled.