This thing is confusing to operate, but after spending half an hour I figured it out. You have to put both wires into the machine and turn on both notches.
The instructions actually tell you to test out just two pads first, so I did that, but it didn't work. I had the pads on my shoulders, and I kept on second guessing myself if it was working or not. Any sort of tingle sensation from the glue, I wondered if it was a pulse from the machine. Then I thought it was just broken, but when I decided to try it with all four pads, and I turned on both the numbers to 1 instead of just one, then it started working, and man it worked hard. At 5 it's downright painful. Just so you know.
Anyway, I'm posting this in case anyone else is having trouble. Still, the instructions are very unhelpful.