Christy,
If you are not using a light then the power goes through the controller making the controller the variable on / of switch.
I have one machine that used a hard wired set of Chicago plugs for the light and motor. The plugs were toast so I converted it to use the double outlet cord block set like the Japanese machines use(d). I kept the ancient wiring so that if I ever find a good set of Chicago plugs I can put it back to original.
Joe