As Mike S said check the hinges are adjusted/aligned. Also I would check that the striker plate is aligned. Also check if it is worn or loose.
Check if the handle or catch rods are bent that would make it hard to open and close.
Good Luck. :)
It would be a good idea to flip the U bolts so there is less of a chance of them being damaged off rocks etc... You may need to make some plates to go over the axle for the U bolts to pass through and tighten up.
ToyotaDyna :) :)
I had this problem last month with my 1983 Dyna. I would advise you fit the new slave cylinder, the old one will let you down when you least expect it.
My master cylinder was leaking but eased off. It was grinding when going into gear slightly but not overly...