I had a 1982 911SC whose driver's seat would never go as far forward as the passenger one, so I couldn't ever get my wife to drive it. One bored Saturday I unbolted the seat and tracks from the floor to see if I could understand the mechanism. There was an ancient quarter ($0.25) wedged in the seat track so beautifully that it almost looked as though the German engineers had designed it that way to limit travel.

Just a thought.