It's not a 15-91 Battle-Axe, but it's a very interesting model 15 derivative. The -91 subnumber indicates the potted motor version, it has a direct drive gear, and doesn't have motor belt. Only Singers had this motor as far as I know, model 101, 201-2 and the later 15s. Yours seems to have an additional features where the top tensioner is on models like 66 and 201 (the black round thing that looks like a bulls eye) What is it for? The switch knob on the bed under the stitch length lever is typical of the Japanese 15 clones, sometimes theres' two push buttons. The original Singer 15s had a setting screw for lowering the feed dog under the base.
Last edited by Mickey2; 11-05-2017 at 06:54 AM.