Chosen Solution
is it really needed? And how can I fix it?
If it’s just the plastic, it shouldn’t really matter.. The cartridges work with or without the cover anyways.. For aesthetic purposes only, it’s up to you if you want to attempt a repair.
If I were you I may be tempted to plug the area that is crumbling with some tac and then just take care when removing or inserting cartridge. I imagine its only use is to align the cartridge