You're probably better off searching for some originals. I bought some new bobbins for my grandmother's 27 treadle a few months ago at the local Sew & Vac which stocks a lot of parts and the bobbins weren't quite as long so the bobbin winder would slip thread off the end on one side. I've been wondering if there's some way to adjust the winder, but original bobbins are probably preferable.