Originally Posted by sharon b
Try winding a new bobbin- clean out the bobbin area , sometimes a small thread can get hung up somewhere . After the new bobbin rethread the machine - I know AGAIN- but sometimes something is just not the way it needs to be . Make sure you have the correct needle for the fabric .
Good Luck I know how frustrating it can be
Sometimes you get a bad bobbin winding by running the machine way too fast. are you using a new brand of thread?
tensions are made for adjusting. just change in small increments until you get the right balance.