Before you pull the wall apart.....
Can you see the rollers at the top of the door ?
There should be a nut on a threaded bolt hanging down (?)
There are 2 nuts one is under the door bracket supporting the door...
the other is on top of the bracket.
With a thin 7/16" wrench , see photo, you should be able to access the nuts and then you can loosen the bottom one to adjust the top one.
Sounds like you need to raise the door, therefore you will have to raise the top nuts so you can bring up the bottom ones.
Try a few turns at a time, and you might have to put extra bend in the wrench to get into the tight space.
Be sure to tighten the bottom nuts or they will come loose and cause more problems.
Don't worry.. the bolt will not turn.
hope this helps
'07 WildCat 30 RLBS ~ West Coast Edition ~
Trail Air - Tri Glide Pin Box
2000 F350 Lariat DRW 4x4 7.3 Diesel 89k miles
Edge programmer, 4" SS exhaust turbo/back,
Tru-Cool Max Trans Cooler, Bilstein Shocks
Vancouver Island, B.C., Canada