Is the bobbin the same one you were using or is it a different one that was wound? I have found that some bobbins seem off center when you put it in the bobbin case and thread it and pull the thread does it pull freely? If it does not or the bobbin does not seem to rotate freely I find it is best to just toss it in the trash. Nothing worse than finding when you are having problems with thread breakage and wondering if it is the same bad bobbin you had in weeks or months ago.