The Singer 9W and 9W-7 were made between 1909 and 1913. They are the Singer version of the Wheeler and Wilson 9D. Singer bought W&W out and continued making the 9D with a few minor changes.
They are excellent machines but do take a obosolete needle, the 127-1. You can substitute the MY1014B industrial needle with excellent results. And some of them take a very hard to find doughnut bobbin. The others use the same bobbin as the Featherweights. My two sew beautifully.
Joe