I finally took the door apart in my shop, since the good folks at Kawasaki in Billings didn't get the job done, and after some poking around, it seemed to me that the outside door latch spring is just not strong enough to handle the bumps of off-roading. I had a spring laying around that was about 4" long with a loop on both ends and of medium strength, so I opened one loop and placed it over the round shaft of the door latch and zip tied the other end to a part of the frame right above the latch assembly. This adds enough tension to the latch that it never popped the door even on the potholes on our rough gravel road that always popped it before. I hope this rather simple fix works for the rest of you ........