How is the mechanism turning? Have you threaded it up?
As far as I can see, model 115 is a general low shank with fitting screw that goes onto the left side of the presser bar. The manual is wrong for your model, likely from a different machine. Model 128 and 127 are general low shanks too, any feet from them should fit your machine. I guess you have a collection of odd bits and bobs in your drawers. Singer are often low shanks, but there are back clamp models, high shanks, and later slant shanks. Other makers had different fittings for the feet, in theory it could be any of a larger number of things.
Manuals are usually small green leaflets with nice illustrations, easily read with out glasses (I'm a bit near sighted though).
Last edited by Mickey2; 04-22-2016 at 03:55 AM.