The doors on my RTV have been getting harder and harder to close.  I took the time to remove the latch, clean and oiled it, then reinstall.  When I reinstalled I left the bolts a little loose and closed the door until it latched.  I then snugged the bolts, opened the door and tightened them.  You do not have much play but I think they may have moved back a little over time from closing.  I have tried to oil them in the past without much luck.  Right now I can close the door and with a light pull it will latch.  I'll just have to wait and see how long it last before I have to do it again.