Joe, thanks again for all your efforts. The 301 definitely looks promising and is at least a bobbin that is readily available. Janey had messaged me about Singer part # A1225 for a featherweight where a 221 or 301 bobbin are alternatives that work. Your test is a good test that appears to be very close to my 1954 Kenmore. I think it's worth a few dollars on a 301 bobbin to try out on my machine. I'll see about getting one and let you know how it works out. - Les