One other possibility. In my 2002 2720SL, the floor of the slide flexed downward in the center when weight was put on it - like someone standing in the center of the slide's front edge, between the tables. If this flex becomes a permanent bow, I can imagine that the carpet on the underside of the slide would come to rest on the carpet on the floor. This would cause a lot of resistance to sliding, and might even lift the front edge of the slide off the floor. The carpets should not come into contact - there is a rubber lip to seal the gap.
The flexing got worse as time went on, and the soft feeling of the floor became unnerving. Denny_A experienced the same thing, and we developed different fixes. Denny's was better - mine was too elaborate - but you can see them both here although the pictures may have gotten lost. The discussion will also give you some insight into what is happening under the floor, which might be helpful.
http://www.trailmanorowners.com/foru...read.php?t=340
http://www.trailmanorowners.com/foru...read.php?t=583
Bill