Here's another thought- Leon has a point. The only Singer machine cabinets I have that have knee pedals, have the 1 button controllers (foot pedals). The later machines had a different controller. The one button controller slips right into the knee bracket without changing anything. When you press on the knee pedal, it pushes on the button on the one button controller.
Singer knee pedals were not wired - they just hold the 1 button controllers. As far as I know, Singer did not use the dual receptacle. I've only seen that on Japanese machines.
Something here doesn't make sense. Photos please.
bkay
One button Singer Controller
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The later controller, which the 247 came with
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