Sorry, I can't provide any additional insight. Thankfully (knock-on-wood), I have not experienced this failure yet, but know that it looms on the horizon for all of us.
Isn't it sad that I consider not rolling down the rear windows on $50k (new) car to prolong the life of a poorly designed window regulator? I suspect that it will fail at the most inconvenient time, like a long road trip, or better yet a huge cloudburst of rain...
E39 - 1998 540iA Sport (11/97 Production)
E30 - 1989 M3 (44k miles)
1979 Triumph TR7, still have my first car ;-)
E21 - 1980 320i (sold at 130k)
E23 - 1986 735i
I am a BMW Car Club of America member, are you? <a href='http://www.bmwcca.org/' target='_blank'>http://www.bmwcca.org/</a>
<img src='http://members.roadfly.com/kowached/bmwcca1.gif' border='0' alt='user posted image'>