bobbin case for portable walking foot machine

[esantoro]

I was in Manhattan today and picked up two bobbin cases for my sailrite/yamata/consew portable walking foot machine. When I got home, i noticed that the bobbin cases I bought have a shorter extended prong than the one that came with my machine. Is this prong, long or short, simply used to aid insertion of the bobbin case, or does it serve another purpose?

Thanks,

Ed

[boyjuki]

It's important to have the longer tab for these machines. I have seen people run the short tab, and it has tendency to slip out of the top groove on the shuttle race