If it's like my circa '57 vintage C3, the latch for the door is a chrome plated metal springy thingie with an embossed button on it, riveted to the end of the body. I'd guess it could be pried up a bit to increase the spring tension. Said latch thingie should have an upturned edge, a sort of tab, about a half inch wide and 1/32 or so inches high that engages a slot in the "keeper" attached to the back. The other possibility might be the keeper (riveted to the back door and folded around the end of the door) might be sprung out so the edge of the latch doesn't engage it well. Either way, it's a pretty simple interface.

Hard to believe it could get damaged enough by wear to abrade the hook portion of the latch away.

Outward pressure on the door from the pressure plate should be trivial, but there is a curved spring that holds the film casette in place that's pretty stiff.

Hmmm -- maybe the door is bent/bowed a bit?

Just some random thoughts ...

DaveT