I bought a used Lionel log loader a couple of years ago. Just now getting around to examining it. Trying to decide whether I want to sell it or keep it. I only run conventional. The instructions talk about hooking up the wires to the A and U terminals of a power supply. Did this accessory come with a power supply? Don’t see one in the box. I was thinking of just hooking it up to the power supply I have to watch it run, but I don’t know if polarity matters and I don’t want to fry the electronics.