Fascinating. Is there a way to trace the lineage/vintage of the motor itself?
My Vinnie is just like that, plugs and all, foot pedal, motor; except the back access plate is silvery, not black. I have another machine same era, which is knee-operated, original. Perhaps a more valid question is; when machines were electric then, did they tend to be foot pedal or knee? Was there an overwhelming majority of styles? Does this help to support whether the foot pedal was original or an afterthought?
And if it was originally a handcrank... oh, where oh where can we find that wonderful old original crank? ;-)