Will tell what I did on my '86. Don't know if the '92 is exactly the same. I would check the switch first as tit is the most likey culprit and easier to replace.
To remove seat back:
1) Remove two screws at the bottom of the seat back.
2) Side seat upholestry is sewn to a plastic strip with two metal clips per side. It is set into a channel on the side of the seat back. The channel needs to be spread (I used a dull screwdriver starting from the bottom) and the clips removed. It is tricky and you can damage the vinyl if you are not careful. It is not difficult once you understand how it is put together.
3) seat back comes out.
To remove the switch:
1) gently pry off the three buttoms.
2) remove the round plastic from the seat back switch post.
3) remove the plastic trim. It should pop off - it does not need to be forced.
4) Two scres hold switch to door frame.
Hope this helps.