I suspect your jam was 100% hinge related. Sagging hinges will allow waay too much pressure on the lock/latch and jam it up. When you reassemble make sure the hinges are doing their job. On my Casita
I ended up installing small metal backing plates on the inside which allowed me to thrubolt the hinges. There's no way the existing mount holes just going into the fiberglas were going to prevent the sag from happening again. Covered up the plates with a leather patch to make it purdy again.