1975 Minnie Winnie Door sticks

[gaugeguy]

Our under restoration 1975 Minnie Winnie's coach door sticks both when opening and closing. It appears to me the problem is in the latch/catch area. I measured across the top of the door opening and found it to be 24"; same for the bottom of the opening. Across the center, where the catch is, measures 23.75"
I see no lateral adjustment of either the latch or catch.
What to do?

Also the roof mounted AC unit sits in a crater in the roof. Any ideas on how to repair and beef up this area? AC unit leaks something terrible when it rains!
Any help, please.