What you have, sad to say, is the header above you slide out is rotten. I had the same problem with another trailer I had. I was 5years out of warranty and was able to get the manufacturer rebuild it with an "in plant repair" and split the cost. I had to take the trailer from SC to IN to get the repair done. Cost me around $3k (my was cost fixed) based on an estimate that was given by a repair shop they sent me to. When they removed the slide out it collapsed due to concealed water damage that they also had to repair. They wound up rebuilding the slide out and repairing the header and replacing the entire fiberglass exterior of the left side. It turned out to be a great experience. That was done in 2006 and it is still holding up. By the way, I wouldn't trust a dealer to do the caulking as most of them aren't to reliable. What you have is a major problem. You must find where the moist is coming from and suspect it is from the gutter and/or roof area some where of the side of the trailer the leak is on. There will not necessarily be a lot of soft spots. Yopu can PM me if you like.