Before you send the wheel back, remove the bolts holding the disc to the disc flange. Remove the disc, and rotate the wheel to see if the runout is in the flange. If the flange run true, you have a bent disc as stated above.
These discs are too thin. As a result, they can be bent very easily. They can also be straightened very easily. If this is the case, there is no reason to send it back, just staighten it yourself. You could straighten a bent disc in about 5 minutes or less.
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