Another possible thing to look for is the large spring in the middle (the one that helps pull the seat rewardward) isn't bent, distorted and bunched up. One of mine was and it caused the seat to get jammed where it wouldn't move. Once I managed to remove the damaged spring I could move the seat - although still a bit difficult. As has been suggested, cleaning and a little lube solved that. The tracks and rails become bare metal from the normal wear of sliding back and forth. That bare metal then rusts and the sliders no longer "slide".Also make sure the carpet isn't bunched up around the tracks to get caught in it.