Or, the needle could be put in wrong, or threaded from the wrong direction. The FW threads from right to left, and the needle is installed with the flat of the shank on the left-hand side (I think that's right). Most likely, it's a thread (a very small one) that is caught in the bobbin works somewhere. After I read everything I had written, I thought I had better double-check what I said. I looked at my FW Manual to verify! I am not the most knowledgeable person around, so others far more experienced may be more help! I tried! LOL
Jeanette