re: How did we all know to fix NES cartridges as kids in the 80s/90s?

100%. Didn't matter if it was Atari, NES, or Sega. A buddy of mine had the motor go out in his PS1 while we were playing Final Fantasy. Almost instinctually, he grabbed it and flipped the console upside down and it started spinning the disc again. Didn't even lose any progress. It was a thing of beauty in the moment, so distinct of a need being met. I was as happy in that moment as the first time I touched boobs.