I've had the same observation with bobbins, and I wasn't planning to use any of these old ones that have a little rust or are the wrong size. Some of my old machines had bobbins that were actually bent. I don't know how that happens. Maybe stepping on them? My treadle machine came with several nice enough bobbins, and I decided to pull off the old thread because it had decayed. Almost every bobbin had 2-3 colors of thread wound over each other. The same was true of my Kenmore that dates to the early 1970's. It's a very nice machine that had every possible attachment, but she couldn't go out and stock up on bobbins?