Everything was fine with my seat until...yesterday. The seat back would move backwards intermittently but not forward. Since I have all "new" parts. I did some more investigating. Since it was intermittently I check for continuity for all the wires from the switch to the motor under the seat. Everything checked out fine. However, while checking continuity, I looked at one the holes where the pins make contact with under the seat. It was loose (or too wide) to make good contact with. I did tighten it up and used some contact cleaner, put everything together and now the seat is working fine.
I now have a spare seat and switch with working parts. If you need any seat part, let me know, I will let them go cheap. E-bay may be next...

Good luck!

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J.H.
'86 300E