Our '08 255RS did the same exact thing. I retaped the top of the slide (Later I did all the roof seams and edges) with the Eternabond Tape. But some day I would like to replace the rear slide wall. We bought ours used, out of state from a couple 8 mos after they bought it new. So taking it to a dealer is not an option.
2001 Toyota Sequoia
2008 Surveyor 255RS
Henlsey Arrow & TruControl Gold
Longest Trip: 2009 - 4 Weeks - 8030 miles Coast to Coast.