How long since you cleaned your machine? Some times my machine just seems to enjoy having some fussing done over it, just some time with the operator and no fabric. If that does not work I leave it alone for a while. I know when I get frustrated, as you must have been, I am more likely to wound myself or the fabric. When I only have a limited time to sew, that is hard, but in the long run safer and cheaper for me. Hope your next session is more successful!