I too have a smaller Lippert sofa slide and started having problems with it rubbing too hard against the floor (carpet).
I dug into it and realized I'd caused my own problems. I have a nylon or plastic piece that runs the width of the slide and as the slide comes in, the bottom slides across this plastic part. over the yeas I have stepped on the slide floor when it was in and this broke the plastic glide. So it doesn't support the slide very well anymore and does as you describe.
So I have a choice; I can either try to replace this plastic part or I can make it better by installing some rollers for it to move on. I've found that short conveyor rollers would do the job nicely and I'm going to try and fit some in next spring.
FWIW, with the slide all the way out I can lift the edge of the carpet and see the plastic part but it looks fine from that perspective. Frm the outside I can look underneath and see the plastic part and the area in the middle thats broken down.
Maybe yours is similar.