Check the condition of the tar tape along the seam where the T-molding (outside flange) is screwed to the top of the slideout. This area sometimes gets small holes worn through the tar tape where screw heads stick up or at uneven points. When this happens, water can get into the slideout roof and into the coach.
The repair is to grind down any high spots and cover the seam with Eternabond.
Also check the seam on top of the slideout along the side corners. There is tar tape there too. It is less susceptible to puncture, but could also be a source of leak. The repair is the same as the other area.
Roy and Debbie
07 Diplomat 38 PDQ