Calculator battery housing had a missing screw. Would have to squeeze it there for it to work. Did that for about a year.
Eventually broke entirely. So I soldered in two CR2032 cell holders and glued them to the back. Am now the proud owner of a Casio fx-4000p with an external battery. I made it rechargeable for a while, but quiescent current draw was too high and it was impractical.
I made a living pretty much just doing math for a short while. It served me very well. I refuse to get a new calculator.
Another time my DVD drive had difficulty opening. I'd have to press the eject button a lot of times before it worked, just did that for like 3 months. Eventually it failed entirely, so I took it apart, removed the magnet that holds the drive shut, cooked it on the gas stove to weaken it, and put it back in. Worked for another 6 months. Was glad I paid attention that day in Physics class.