If it is taking very large stitches and dragging, the encoder wheels may not be rolling on the frame correctly. Check to make certain you did not tighten the encoder wheels too tightly and that they lay on the tracks as you move the machine. Also, double check the plugs into the encoders to make certain they are in all the way. If this is the 9" MegaQuilter and not the 18.8, the speed slider should be in the middle position.