After some research, It appeared that I had a Singer Model 115 here. This is a full rotary hook unlike the "Oscillating hook" of the Class 15 machines. Wow, was I surprised! Unfortunately, the bobbin case itself was broken.
These old bobbin cases are virtually impossible to find. I did luck out and find some parts that did allow me to rebuild this original case and is now in working order.
So, here ya go. a 1918 Singer 115-1, treadle sewing machine with a full rotary hook, sporting the "Tiffany" or "Gingerbread" Decal set. These machines were made from 1912-1935. It sure looks like a 15-88 to me.
And I am never happy untill I get it sewing that perfect stitch.........