Again though, those will be the low quality bobbins. Apparently the quality control is the first thing to go on the low quality stuff. I don't buy anything labeled Singer if I can help it because all they seem to stock is the lower quality bobbins. I think Jenny's doing the same thing that I do - order only the higher quality so you don't get the come backs. I ordered a bunch of 66 bobbins from her before I set up with that distributor in Canada and never had a problem with hers. They're also heavier than the cheaper ones and feel closer to a vintage bobbin.
I did this when I was in computers as well. I always told people I didn't build the cheap machines. If they wanted cheaper than my machines, they could pick it out - get the extended warranty - and I'd configure it but I wasn't going to be their warranty source for a cheap machine. I still have machines that I built more than 10 years ago that are running and only got retired because XP is no longer supported and the machine didn't have the ooomph to run the latest operating systems.