Originally Posted by
Caroline S
Here is an Internet link with some good pics of the Singer 306. About half way down there is a picture of the bobbin assy. According to this site it also takes a different bobbin kind of bobbin. I will know more about it when I pick it up and do a little more research.
http://possumjimandelizabeth.com/xhtml/collect_sewing_sing306.html
I don't see anything strange in the pictures. Like Joe said, bobbins are easily purchased on the net. If you collect vintage machines for a while you'll find each one is made differently and has there own idiosyncrasies.