I have a similar issue with my Windsport 27B. Here is the solution from my dealer...
First. Extend the slide about 6 inches and return. Then, if that does not bring it in enough, just barely engage the extension, about a second or so, the slide will hardly move (just enough to hear the motor engage), then return. Do this a couple of times. This should readjust the slide and bring it back tight.
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