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I have not seen your exact door to know, but I'm going on the assumption yours is one of the older wood built doors that has had some water damage to it. This creates a sagging door, meaning the door is no longer square at the corners, it has turned into a parallelogram and it will not fit into a semi square hole (frame) in the camper.
You can measure the door to find out if this sagging has happened. I'll try to explain this in words, if you cannot follow it, then ask away.
Open the door so it is only supported by the hinges.
Using a tape measure, measure from the top hinge corner diagonally across the face of the door down to the opposite side, (door handle side) lower bottom corner.
Then repeat the process at the top non hinged corner, diagonally to the bottom hinged side corner and compare the two numbers. If the door is square, the two numbers are very close to equal. The more out of square, the larger the error.
You need to find the edge of the door in the same spot where you measure to not have error in the numbers. If the outside of the door is too beat up at the corners, then try the inside surface of the door. When the door is true square, the diagonal corners are equal.
You can also check the door frame diagonally to see if it is square.
There is something maybe even quicker, open the door, and lift up with you hand on the non hinged side. If the door flexing up and down, the door has become so weak it will not hold itself square and it is not going to work right closing. Rebuilding the door has worked in the past if you have basic wood working tools. Several here on the forum have done this.
And there is also camper frame sag. This happens on the newer camper and I'm sure on the older campers. The newer all metal framed doors hold being square rather well. But the camper door frame then turns into a parallelogram and the door will not close right. This is somewhat what Tin above was talking about. He can tweak the camper stabilizers to bring the door frame back to more square and the door will then close. This issue I have had to remove the entire door frame, reset the door frame in the camper, and then the door would work better. The floor plan of the camper changes how bad this problem can be. It seems the door being way back behind the rear axle can be the worst offender for frame sag. The frame sags over time and is no longer straight, and the further the rear overhang, the worse the problem. I have also had it happen between the wheels and the tow ball. The longer the camper, sometimes the larger the frame sag.
Hope this helps.
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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