If you park the 4th Pinch wheel (which is what holds the material down on to the grit wheel, which is underneath) and use the 3rd pinch wheel on the left side of your media, does that work? If so, you probably have a cracked or broken pinch wheel assembly. The last time I checked, Graphtec was out of stock on those. You may have to get along with just 3 pinch wheels.