If improperly used...
Biggest problems are carts partially inserted, banged on steps or curbs, pulled partially out and then the boat set back down on them. Cart posts can leverage the scupper walls if only partially inserted or inserted under loads.
Carefully and fully insert into scuppers.
Use the cart keeper pin.
Avoid steps, rocks etc that can cause a jarring load on the scuppers.
While we are on the subject, I'm new to the kayaks, and have not used mine for the first time, I know I can well the thing all the way to the beach, fully loaded. But once there what? time the kayak and pull the cart? I know i'm going to be securing my cooler fine and all but aint it a bit weird doing it like that? or do you float it in the surf deep enough to pull it under? this also make me think I need to be too deep.
Sorry about the newbie questions.