Make sure the rotor is fully seated against the hub. I don't think the studs should spin because their flanged "heads" sit in a groove on the backside of the rotor and keep them from spinning. If they are spinning then I would think that is because the rotor is not bottomed against the hub. Push it in towards the hub if it's got any wiggle in it and see if you can get the flanges of the studs seated in the groove, and then go after the nut. At least that's my recollection of how my 400f is set up....