I'm not at my home computer to see the numbers I have. Can you give me the numbers of the "wrong" parts? Actually, Singer would sometimes give a new number to an old attachment. I think one time I saw the same number foot but with slight differences. Did you check with the singersewinginfo site? Also I've been collecting many things off the net and have researched even more. I can try to find a parts list for the 600 or 700 series for their feet numbers. It would give some more options for the same foot.
Janey - Neat people never make the exciting discoveries I do.