[anijet]

Just had the same problem on the off door side. Determined the belt line seam about 8 inches above the electric cord door was leaking. The lower sheet metal pan is not tucked under the fiberglass panel but rather on top so if the belt line caulking is cracked water can run right in. This seam is just above the floor line. I removed the trim piece and took out the electric cord door frame. I placed a blower so that it would blow up into the wall and let it run in the sun for three days. Then reassembled everything with fresh sealant. I'm now in the process of stripping and re-caulking all the exterior seams. I'm about half done and after figuring out a method it isn't as much work as I thought it would be. As Joe mentioned, check all the roof seams also.

Edit: Just re-read your opening post and at first I missed that your problem seems to be in the slide. I think I would still try to dry out from the exterior belt line.