Whirlpool ice makers
I've learned more about those things than I really cared to know. I just recently had to replace the water valve in mine (it's on its third valve now, in 12 years). I've got two timer wheels that I modified for higher water pressures, a spare mold, a spare motor, etc. I can now probably diagnose just about anything that can go wrong with one. The good thing is, there are so many in use that parts will probably be available for as long as I live.
BTW, I did not realize that Servel invented it. My grandmother had a Server gas fridge -- not one with an ice maker, unfortunately.