I took a bit of time recently to take apart two of my Atari Jaguar joypads. The rubber/plastic screwhole covers, over time, had disintegrated and melted into a gooey, sticky mess on the backs and front of the joypads. It was gross.
If you’ve got old videogame equipment (10+ years) and you’ve noticed the rubber/plastic screwhole covers on the backs of the units or controllers getting soft, I recommend taking them off and avoiding the cleanup you’ll be facing in the next couple years. Otherwise, you’ll have to do what I did and use Goo Gone. The good news is that Goo Gone is amazing and it’s fairly cheap.