Getting a good used one (at least the motor unit, about $100) is your best bet, That is what I did and then you have time to repair at your convenience. The videos show them replacing either the ring gear or the driving gear set which gets the mirror working again but doesn't really fix the problem. Right and Left are different.

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1988 325is (purchased new) sold
2004 X5 3.0 2005 X3 2.5
2008 X5 3.0 (new to me)