Check for cracked wires in the door hinge area. You already have a strike against you with the degradeable insulation and the extra movement at the hinge might be just enough to crack it giving you a short. BTW, the back and forward function motor operates off the same power and ground source as the head rest in the seat switch on your door.
I seriously doubt you actually have a problem with the seat itself. It is more than likely the switch or the wires running to it at the hinge.
Here is the cut wire I found on mine (at the hinge) - same symptoms as yours.
Here is the repair I did on mine; although, it is not necessary to pull all the wires back. You can just tape them.
