thanks Billyraymallard. It will be very interesting to see if the deflector pulley repair works. I now have about 23,000 miles on my X5-50i and am still living with the annoying whine. The Dealer has successfully worn me down to the point where I cannot waste any more time arguing with them because they are a moving target. They don't follow up on their promises and are shameless. I've tried other Dealers too and they all stonewall me on this issue.
I'd love to solve the whining problem and hope that you have discovered the real cause. Good luck.