Ours did a similar thing when we were in AZ for the winter. I called HL and they had the material in stock---just ask how long I needed. I measured the slide length and HL sent it out the next day. I did 3 tops of the slides, taking off the old, cleaning the tar like stuff off the slides, installing the new, and caulking, took about 1/2 day. One thing I learned, there is a screw holding the seal at each end---in order to put that screw back in the same place I used the old one for a pattern and drilled the hole into the new one prior to installing---you will see when putting the new in place you cannot see where the screw should go, but by having the hole predrilled--no problem
al
currenlty in crystal River, FL