I can't tell by your picture is the crack on the inner or outer top of the slide. If it's the outer part removing the slide topper wouldn't help. Mine had a slight leak on the inner part of the slide top. I opened my slide about halfway then removed the interior trim. This gave me more clearance between the ceiling and the top of the slide. I was able to get all the way across the slide and seal the crack. But as others have stated before go back to the dealership and try and resolve it there first. Anything you do may void the so called work they might have done. Then you'll be stuck to fix the whole thing. Good luck let us know how you make out.
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