[sueandjerry]

Our rear slide in our 2008 5272 BT Cruiser leaked terribly. Stepped in about an inch of water on the carpet one evening. We think it was because of the horrible job Gulfstream did with the gutter material. It did not meet and dripped down onto the top of the slide cover, pooled on the roof and ran under the gasket that did not meet the top of the slideout.
It also was not sealed, just left with a large space and a gob of goo.

Our local approved repair shop installed an L-shaped row of a flashing type plastic and sealed it solidly around the top and both sides all the way to the bottom where the slide meets the gasket when extended, and fixed the placement of the gasket. They told us it was the fix they were using for the Winnebago slides that leaked. They did both our slides because the front one was also leaking a little bit right at the front. The had the coach 4 days. Gulfstream covered the cost since we are still under warranty. We are very pleased with the repair. Thankfully we were camping someplace very hot when we had the leak so it had plenty of time to dry properly so we don't have a mold issue to deal with later.

We have not, however, had any trouble with ours leaking when closed. Good luck, those leaks can be tricky to find.