So as for what the clatter is, it's just the spline drive has a little play in it.
https://www.youtube.com/watch?v=yA7s30Zwbo8
Sorry for the muffled comentary, but that is all what is wrong with this one so I'm assuming thats the same as what is wrong with mine. I've reassembled this one now and put thread lock on the spline so as to take up the play and possibly swap it at a later date.
https://www.youtube.com/watch?v=J0ekAh1kwIg
I can only assume that either the vanes or the outer ring are magnetic so keep the vanes out.
I hope that helps any of you guys out there.