i have the same problem in the same place. i was thinking about, while the car is stored for the winter, taking all the rear mechanisms out, heating the shit out of the catches and bending them ever so slightly to tighten the grip. i have heard that if i plung the hot part into cold oil (sounds fun on many levels) it will temper and therefore not lose strength.
then i could try my hand at powder coating in the kitchen oven!!!!! i may end up single but damn would my latches look sweet!
i don't plan on doing this for a few months so i am probably of little to no help.... sorry!