Originally Posted by
Mrs. SewNSew
I do what Miriam does. I've run into this a few times. I use a plain white string and floss through the thread guides to be sure nothing's catching. Then take the top tension apart clean it well and put it back together. That usually solves it.
I've learned the hard way do both the top and the bottom. There is usually dried oil on the pin in the tension, too. That's why I pull it.