The spare used Singer 301 Bobbin Case that I found in a Singer bag in amongst the extra goodies that came with my latest 301 appears to be in fine condition, but it has a layer of oily lint build-up in the back of the case. I suspect that the bobbin was possibly getting bound-up, or the case became difficult to latch, so the owner bought a new bobbin case for the machine.
There’s a good thick layer in there, so the owner was probably having problems with it. It was certainly a nice surprise to find it, and really helped to make my $80 purchase even more of a bargain.
CD in Oklahoma