There is an adjustment for the height of the pin, which inserts into a stop with a hole in it in both the open and closed position.
You have to pop off the wooden cover over the top of door, which covers the track. It is held in with small staples. If you pop it off from the inside against the rail, you should not mar the panel. If you are careful you only need to pop off the side towards where the door closes (handle side), but it's easy enough to pop the whole cover off and replace it.
Once off, you will see a channel in the rail where the door travels. Using a wrench, raise the height of the pin mechanism until it is securely in the stop hole (test both open and closed positions - one adjustment will address both).
Reattach the panel along the top piece of wood nailer against the ceiling with small finish nails, or small staples if you have them. Then cover the holes with matching wood putty.
I did mine this way, and the doors now stay closed all the time when traveling. Looks as good as new.
'07 Winnebago Journey 34H - CAT C7, Koni's, MCU's, SS Bell Crank, Safe-T-Plus
'07 HHR Toad, SMI AFO, Blue OX