BINGO ! ! I bought a 30 ft. '05 Grand Surveyor last spring from the original owner. They told me that there had always been a problem with the slide, the front end would always start to go out then the back end would "jump" incrementally and would catch up. I laid on the driveway under the slide and had my son operate it. The bottom of the slide is covered with a type of material which looks like roughly woven meshing, then rubber coated. There are two (2) sets of rollers which this is supposed to ride on as the slide opens and closes. And--YES--it is the "Lippert" above floor type system. The back roller had locked up, rubbing a long tear in the rubber coated material, and eventually into the wooden flooring. Therefore: NO rolling of the unit as it went in/out, just gouging into the wood. I removed the damaged material, filled in the gouged out wood with some "wood bondo" material, and sanded this smooth. I removed both roller/leveling units to make sure they were free rolling and adjustable, then put them back in. I cut some 18 ga. sheet metal, app. 10" wide x 20" lg., to put where the rollers had been rolling (?) under the slide securing these with rd. hd. wood screws so the rollers would not hit the screws. After adjusting everything back into position, this unit moves nicely. I cannot understand how the manufacturer's think that these rollers would move on this rubber coated material. Hope this helps someone.