Looking for Nelco bobbins
Hi everyone, I am a newbie to this forum and I'm hoping someone here can help me. I have a Nelco sewing machine, gifted to me in the 1980s, Model SZA-221F. It came with 4 metal bobbins, and I lost one, so now have only 3. I have hunted everywhere for bobbins that will fit this machine, with no success. The bobbins measure 21 mm in diameter, 7 mm high, and they are very slightly convex. Does anyone know what type of bobbin matches those measurements? Thanks in advance for any info you can give me.