Originally Posted by Weedwoman

I went through the bobbins I had for the 306k and I think only one of them were vintage, the other 4 seem 'fatter' and their thread holes are larger. Anyway, I put the vintage one back in and it did 'snap' and I was able to sew without breaking thread or cussing. I guess now my quest will be to find a few more vintage bobbins for it as I hate having only one bobbin for a machine. Anybody have any to sell?