Okay you can have several things going on. I have learned this the hard way with my 2 brothers. First only buy brother bobbins, go to a brother dealer, prices are good and you will get the right bobbin. I know I did the same thing bought the size that they said at JoAnnes and they aren't the same size. Also if you are using the net your tension might be to tight try with out the net. Your upper tension needs to be between 2 and 6 I would try 4. Last but not least, make sure the embriodery thread slides easily through your needle, because the eye might be to small. I hope this helps.