Aluminum is great but it can crack and break. It is not bullet proof. I had an 1150 that had to be repaired for just this reason. The entire slide had to be removed so they could get access to the rear corner. It was flexing so bad when you lifted and lowered it....I'm surprised it didn't damage the filon siding. I too have seen the insides of these campers and I just have to shake my head...I would never buy another RV...I have just decided to build mine myself. So if there is any issues I know who to talk to and who will fix it. I know not all have that ability but after seeing stuff like this it's worth giving it a try rather than trying to put a band-aid on something that was not built correctly to begin with...good luck on the project.
