This pic shows the door off the tack
I had that happen on our new T2499 and on rare occasion on our T310SR.
Here is what ours does, yours may or may not be this way but is a place to look.
Screwed up in the cieling is the track. And like Sunline Fan said see if it is bent open. Ours was not but yours may be. Look for a little trolley wheel set. If it is still in the track, then it is not a bent track. If the trolley is stuck to the door, then it might be a bent track.
On ours there is a little trolley that rides in the track. In the center of the trolley is a threaded stud (screw) that hangs down to meet the door and there is a nut or other fastener on the bottom of the stud. On top of the door is a small white plastic lever type clip.
If you slide that lever, it pivots and allows the hanging stud to come right out of the top of the door. Sunline actually silicone'ed our lever shut so the lever would not vibrate open and let the door fall out.
You do not have a lot of room to see up there, a small mirror and a flash light looking at the top of the door you may see the white plastic lever pushed out of the way and the stud hanging down from the trolley. If this is it, then rotate the lever full open. The lever will be swung out away from the side of the door.
Then shove the door and stud back together and it door to hangs in the door hardware like in a key hole slot. Then flip the lever over.
Ours was built in November 2003 and this was what Sunline was using for door hanging hardware at the time. I do not know how far back that hardware existed.
If you see the little trolley wheel with a threaded stud hanging down in the track, odds are high it just poped out of the door. That little trolley may be slid all the way one way or the other. It might be hiding on you.
Hope this helps and let us know how you made out.
Current Sunlines: 2004 T310SR, 2004 T1950, 2004 T2475, 2007 T2499, 2004 T317SR
Prior Sunlines: 2004 T2499 - Fern Blue
2005 Ford F350 Lariat, 6.8L V10 W/ 4.10 rear axle, CC, Short Bed, SRW. Reese HP trunnion bar hitch W/ HP DC
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