Putting it all Together

The primary problem to making the sewing machine work was getting a motor control connected and the barrier was a lack of the specialty plug that connects the speed control to the machine. That power source also powers the light.

The trick is that the power to the motor is modulated to vary the speed from zero to max, whereas the power to the light is constant at max.

So I whipped the plug receiver off and took a look.

Definitely not rocket science.

I made a simple plywood cover for the hole to re-use the existing screws that threaded into the machine case. Next I used two different colored wires to identify the motor from the light power, and wired the junction box appropriately using a specialty plug receptacle and plug with one lug at ninety degrees to normal. After color coding the plug end to wire color, and assuring the wrong plug cannot be inserted in to the wrong socket by putting a bit of glue in the slot, the junction box can only be connected one way without the willful assistance of a hammer.

If you do manage to plug it in backwards you get a foot control on the light and a full speed ahead motor. But no electrocution.