Slide out goes out but struggles and won't come in

I spent several hours trying to solve the same problem you have. Super cleaned all the tracks, checked electrical connections, replaced the slide motor,replaced the batteries. No success! Finally I crawled under the slide and had my wife retract it. A section of the lower gasket was being pulled into up into the slide area but would go back into place as the slide went in. I cut it out and the slide worked perfect. $1000 dollars and 5 or 6 hours it was fixed for nothing. Good Luck.