ok I went to that site and down loaded the manual, good thing you have your own because the one they have sucks, not worth your time. Anyway, looking at what I could see of the pictures (there was no words in the whole manual) it looks like your bobbin is the type that has the tension adjustment on it. It will be a tiny screw, maybe you put in together right but now have to play with the tension screw on the bobbin the get it right again. If you send me a picture of it I can look at it better and tell you more about it. My normal email is
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