***I have no idea about cars but give this a try.***
See if there's anything blocking the seat from moving. Seems simple but even a spec of dust can annoy these electronic seats. Also check fuses as some of these seats are driven by two small motors instead of one and a single motor doesn't have the power to push the seat forward and backward on its own. Also, give the mechanism a little bit of WD40! Oiling parts of something as old as this may surprise you! Otherwise, I wish you good luck on repairing the seat!