Maria's other picture of the pocket stop:
http://4.bp.blogspot.com/_iZSRedBZ9n...Repair+021.jpg
This shot seems to show a frame member at the top of the pocket. It does seem to show that the lift bars do support the weight of the shell on a frame member. There also seems to be a heavier guage sheet aluminum as well as the aluminum skin on either side of the wall section at the pocket. When it stops raining, I'll take a peek at the underside of the pocket and see. This is Vancouver BC, so that could be awhile. Next time I have it open I'll take out the acorn nut and bolt and try to assess the condition of the hole.
Edit:
I just took a peek at the torn outer skin beside one of these acorn nuts/pins. There is, indeed, a heavier aluminum plate behind the thin aluminum skin. I believe the hole in the thicker plate may be a elongated slightly, but the outer skin seems to play no role in structure, as I would have expected. At this point, I suspect any repair here would be purely for cosmetic reasons.
Thanks to Bill for making me take a second look. As you said, the lift arms should be connected to the "rigid box". I was trying to figure out what part of the rigid box the lift arms connected to. I could not see any 1" frame member where the hole was for the bolt. A second look led me to the thicker plate part of the rigid box.