I thought I'd post a little encouragement for those that might have an inoperative 6 way power seat in their car. The fix is relatively easy, and VERY cheap.
I just purchased an original (not re-painted, nor reupholstered) 64 Sedan De Ville 4 window. When I purchased it the front seat was adjusted forward and tilted down in front; two of the worst positions for me, so I had no choice but to attempt to repair it.
Pushing the switch in each direction brought the sound of the seat motor, but nothing else. Even a few "technical taps" on the transmission did nothing to cure it (I was hopeful but unrealistic).
The front seat came out with difficulty as the position it was stuck in did not yeild enough room for a socket wrench to be used on the seat bolts, so this was a hand tool, closed end wrench operation. Ugh!
I was careful to disconnect the main power connector (about a 7 gang connector) and the power for the cigarette lighters (a single blade connector), and removed the side seat trim before I unfastened the 8 seat bolts. After the bolts came out, the seat wanted to tilt rearward, so I let it do so. It rested comfortably and safely on the lip of the rear seat cushion.
The transmission comes out relatively easily with the unfastening of the two bolts that hold it to the seat frame, followed by the unfastening of the 4 strange screw heads the attach the cable retention plates to the transmission.
Upon opening it up (3 screws) it was at first not so easy to observe the dried grease, as it was mostly on the gear shafts where they interact with the round dogs. The dogs are supposed to be free on the shafts, but two of the three in my unit were stuck solid to the dogs, thus preventing proper operation.
Cleaning was accomplished via brake cleaner and carb cleaner, followed by lubrication with Vaseline. Re-assembly is straightforward and while installation is a little tricky, it all fit together and allowed itself to be bolted up to the frame. NOTE: the motor and transmission are connected by a plastic donut that has a filled in face, matching a flat surface on the motor-to-transmission shaft. Make sure they match when you re-install.
That's it. My seat works perfectly now. YAY!
Oh, just to be clear, if I can do it, so can most anyone.
Good luck to all who try this.