Could be the roof or camper wall have gone out of square but I think I'd look at the front panel. The oem design works well but I think the geometry is critical for best function. Plus with the rear panel not being permanently attached at top and bottom there is less control when dropping. Wouldn't take much skew to throw out the rear over that 10.5' or so of roof length.Dobba84 said:
I have a similar panel arrangement with a rebuilt standard front and top only attached rear panel. I always check the roof fit at the rear before latching down, just in case. I haven't the problem you are showing but I can imagine that it could occur with your current set up. Others with rebuilds might chime in here.
Good luck with the rebuild !