Do you have a darning or free motion foot on? A darning foot is a little circle or horse shoe shape foot that hops on a spring on the quilt top. This is used with the feed dogs lowered or covered. You would have to really pull the quilt to hit the darning foot. You are more likely to be hitting the throat plate by the feed dogs. Make sure your machine has the zig zag plate on instead of the single hole plate. This gives the needle a little more room and you are less likely to hit the plate. Make sure that your quilt sandwich is all supported on your table so there is no drag. You will need to either move your quilt slower or increase the speed of the machine.