a member here (kpecks, i believe) had one of the rollers on the bottom of his FWS break off...it was restricting the full deployment of the slide, and causing air intrusion...
i would have him look in the gap, when the slide is almost all the way out and then ready to drop, very carefully, for anything like that...check all the rollers.....gotta use a good flashlight and get down in there close....also check from the outside....
i suppose it also could be an issue with the chains on either end of the slide.....could be something binding there....
EDIT: here is the thread on the roller breaking....
http://www.irv2.com/forums/f103/mino...-421653-2.html