If you can get a piece of the rubber seal that you have to the slide wall now and back off screws holding metal strip, if you have one, extend the strip down beyound the slide wall. Than peel back strip and place some sealent at bottom edge of slide wall behind the rubber seal. This will help to drain any water coming down bottom edge of slide from getting into the coach area if your coach is not that level.
One other thing as your slide moves out the rubber seal will act like a wiper and peel to the outside sometimes it does not turn on slide wall completely run your finger up behind seal so seal is tight to side wall of slide and there are no bends in seal coming down wall.
If there is than water will get behind seal and run into the coach on back side of rubber seal.