As every vintage sewing machine hunter knows, a lot of times you buy a machine and the seller insists you take the cabinet it's mounted in, because they just want it out of their garage. The first few times that's fun--hey, free desk!--but soon you have more cabinets than you know what to do with.
If you have a Singer that's been wired for cabinet use, it will have a "single lead" power cable with just one set of wires going into the terminal plug. Here's the one from my latest acquisition:
As you can see, this one's in poor shape and needs to be tossed. The wiring insulation looks like it dates to the Eisenhower administration and you can see bare metal. But before we get rid of it, we're going to "harvest" the Singer terminal plug, so that later we can easily--and inexpensively--make ourselves a new power cable.