I've had the same problems, and have worked on it lately, but haven't had it out since the work. What I found was the aluminum the roller wheel was attached to was bending which would cause the wheels to come off the track. This also caused the door to hang a little lower than normal which caused the locks to not work correctly.
I reinforced that area of the aluminum piece where the wheel attaches. Then, readjusted the locks. I also made some straps out of Velcro that go thru the handles to lock the doors in place when traveling.
And one more thing....I had trouble with the bolts coming loose that held the roller wheels on, so I used red Locktite on them when I reassembled.
Time will tell if these things improved the doors.
Also, see this thread: http://www.airforums.com/forums/f44/...ors-94076.html