Why didn't Japanese N64 cartridges fit in American consoles?

1UPcard Cleaning Kit Compatible With N64 Console how to clean n64 cartridge slot In this quick video, I show you how to clean the pins on a Nintendo 64 cartridge slot how to play a slot machine Today I show you how to take apart and clean a N64 cartridge This is a good idea as these

how does a slot machine really work Well this was my second attempt at relocating the cartridge slot, and both seemed to fail despite my ultra precison on the second attempt