The pinch wheels need to be centered over the grit shafts below. So pull out your mat and make sure that at least the outer two that would be near the outer edges of the cutting mat are ALSO over those grit shafts beneath.
If that's not the issue then report back your cut settings and details about the material you're cutting. By the way, you might benefit from referencing the following user manual I've written. The Maxx Air model is VERY similar to the Silver Bullet and is also made by Foison. Much of what is in this UM will probably also apply to your model.
http://www.iloveknk.com/support/knk-max ... port-page/
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Sandy McCauley
Manager of Customer Relations and Education for KNK USA
Owner of
http://www.iloveknk.com/