Also, any Singer machines made for INDUSTRIAL/COMMERCIAL use are not covered here at this time.
As I work out more parts to this template I will update in the future. You have indicated that your machine has the large Knob/Dial on the front of the arm.
You have indicated that your machine is Electric Powered. Is there a RUBBER BELT that connects the motor to the Hand-Wheel? You have indicated that your machine HAS a Rubber Drive Belt.around the late 1950's on-ward, most Singer Sewing Machines had their Model Numbers clearly visible on the front or base of most machines.Prior to the late 1950's, most Singer machines DID NOT have the Model Number anywhere on the machine, thereby making it very difficult to identify.If you have the Treadle it is a Model 15-96 and if it is Hand-Crank it is the Model 15-98. The Tension Adjustment Dial/Knob should be facing toward you as you have indicated and here is NO large Knob/Dial in the middle of the arm.Now locate and look at the Slide Plate and Needle Plate.If your machine is the 3/4-Size model with the 12 to 13 inch Bed (30cm to 32cm) then you have the Model 28.