It's a weird one, on a 1990 UK E32 auto. Passenger mirror should dip when reverse is engaged. Recently no dipping, and a weird whining noise ... which it transpires, is coming from the motor under the driver's seat, which then can't be moved.
Now both reversing and trying to move the driver seat start the paralysis.
It's intermittent (so of course it didn't do it when I put it in to the repair shop) ... and now it's 90% always there.
There was a previous posting similar to this, but I can't find it now.
Any solutions guys?