... THANK YOU. I just recently got a 3870x2 back from RMA, and it JUST went past the warranty end date. Rather than try and deal with another potential RMA and month-long wait, I started searching for a solution to this problem and came upon your post.
5 minutes later, the fan is good as new. In fact, I was lucky and the plastic ring had just slipped off, but was still in excellent shape. I clipped it back over the column and all is well.
Again, thank you so much, I would have just given up