i have the same problem and if you operate the seat when its off of the car and you look at whats moving and what isn't, one of the gears that is suppose to power the other, non-powered side (the seat motor is only hooked up to one side), doesnt work anymore. i assume this is a part that wears out after years of use. the easiest way to do it is to get a new power seat motor, complete with the whole assembly. otherwise, for now, you can manually adjust it. there's a 10mm bolt on the right rail if you feel for it with your right hand as you're sitting on the drivers seat. you need a socket wrench to adjust that bolt, but you'll be able to manually adjust it forward and back through this bolt.