Could it be that 3rd party carts for the Saturn had thicker PCBs than the original ones, thus widening the slots over time?
People suggest this all the time. I don't know where this idea came from, but it's not the problem. My white Saturn has never had a 3rd party cart in it and the slot is just as dodgy and f*cked up as the black one I have which had a PAR in it for the first two years of its life. It's a completely POS cart slot.
I've never heard of anyone having to replace controller ports though. That's completely new to me, and I have a full 10 player Bomberman SS setup that my old fan club used to take to conventions all around the country for tournaments so you'd think I'd have seen this problem at least one time if it was a regular issue. I absolutely love the Saturn and its overall probably the most reliable CD system I've ever owned, but that cart slot just sucks.