Can you hear it continuing to move or does it just start and then stop in half a second? I had a problem with mine once where the worm gear on the bottom that moves it was just really dirty and bound up after it moved a little bit.
It's shot, you need to buy the upgrade kit from LMR. I did mine last year and it fixed perfectly. Theirs is a heavier duty one then stock. It does need a little bit of modification on your part. But there are videos showing you how to do it. Pretty easy I think.
Another time it broke it was just the switch that was bad. Again take it out and flip it over and you will probably see what needs to be done. You can replace it with a regular manual slider if you want or else its not that hard to find someone basically giving away a stock set of seats. I tried to sell mine for half a year with a make an offer add and never got a nibble. I ended up selling the rails and scrapping the rest.
When I first bought my 96, the seat wouldn't move forward or back. When I toggled the switch back, I would hear the motor. When I selected forward, there was no sound at all.
Turned to be a bad switch. When I was toggling it back, it was already all the way back (that was why I could hear the motor). The forward function of the switch was broken.
Oh, fyi. If you move the seat all the way up, you can probably see under the seat and may be able to tell what the issue is. Also, that will give you better access to the bolts that hold the seat in place (for removal)