2000 Designer Slideout not sealing on top when extending

[BumpaRoy]

I just bought a used 2000 Designer 3310. It has two slides, one in the main room and one in the bedroom. The bedroom slide seals nicely and the fascia board on the slide trim seals up flush to the wall of the trailer. However the main slide seals at the bottom, but at the top there is about a 1/2 to 3/4 in gap between the fascia board of the slide and the wall of the trailer. Again, just at the top. I can also see light from the gap. It as if as it is being extended, something is holding back the top in the last 3-4 inches in the extension.

I check the slide awning, at it has awning left to extend and the awning tube does rotate if I manually turn it. So it doesn't appear to be the awning. The camper is level. Any ideas??