A picture of the outside Aluminum angle would be helpful. We had a 2010 Wildcat that had same issue. The aluminum extended past the edge of the slide and was not sealed along the top edge and where it met the outside edge of the slide water would get behind the angle and would drop on the floor when it was extended.
Removed the aluminum, sealed it properly and cut about 2 inches off the end. This probably was not necessary after it was sealed, but never had that leak again.