Purplefiend,
I see that your Singer 237 had the external motor that you removed so that you could use the machine in the treadle. Very smart of you to do and easy. At first I thought it was an internal motor that you removed. So, it seems that if the machine has an external motor, not pot belly (internal)motor, the machine can be easily converted to treadle. Are there any other Singer zig zag machines like the Singer 237 with the external motor? Or is this the only model that Singer made that had the external motor? I like what you did and would love to find a machine with the zig zag that can be used in a treadle.