One of the parts of motorized vintage sewing machines that seems to suffer most is the wiring. The insulation is usually dry and crackled, and often the wires have been cut through.
|Foot controller, plug for electric socket, plug for machine. And a mess of old wires|
In this case, I recommend taking it all out and replacing it with modern wiring. Be careful to note which wire goes to which connection.
You will need two pieces of wire: one about six feet long that runs from the wall plug to the sewing machine plug, and another about four feet long that runs from the foot controller to the sewing machine plug. Cut the wires near the wall plug, open up the plug, and replace them with the new wire.
Turn over the foot controller case and remove the screws in each of the four feet underneath. Turn it upright and disconnect the two wires there. Replace them with the new wire.
|Foot controller underside|
|Foot Controller disassembled|
Lift the three connectors from their slots. Again remembering which wire goes where, cut the wires and pull the old wire out of the plug, and remove the old wires from the connectors.
|Sewing machine plug - connectors and old wires|
|Sewing Machine plug - connectors and new wires|