Welcome to QB, Les. From my understanding, your bobbin may be part #A1225. I think it may have the same dimensions of a Featherweight bobbin. According to
https://www.sewingpartsonline.com/pr...-bobbins-45785 an alternate part number is A1225. While they are out of stock, given the part number you should be able to find them elsewhere. Perhaps if you know someone with a Singer 221 (also known as a Featherweight) or 301 (which takes the same bobbins) they would let you try in your machine. Do you have one to compare?