Seat motors '91 190E 2.3 - FYI for DIY
The driver's side seat no longer would move the front or rear down, a click could be heard trying to move in other direction. Fore-aft worked ok, and seatback would recline, but intermittant return to upright. Removing seat and testing motors verified they were ok.
I disassembled and tried to work on seat switch, but serviceability poor and no success. Verified switch as culprit by a temporary swap with switch from passenger seat. Anyway, new switch solved the problem. First part recieved was incorrect - mechanically identical, but wrong plug pattern; apparently for a '90. If you do an junkyard swap, be aware of this issue.
Switch removal procedure: pull buttons straight off, pry off plastic c-clip under seatback button, pull out front of switch trim from door. Switch attaches with two screws you dont want to drop, then plugs pry off from behind.