The electric cord that went with it would have two female ends that fit over the pegs in those two holes in the metal cover on the base behind the machine. My husband rewired the cord for me. He used what he had on hand- so I have a white cord now!
The ends are very hard to find - so if you don't have them you may want to rewire it - the you could wire for a foot control if you wanted to bypass the knee control. The bars can be found on ebay - you need the one with the round female end (not the flat male end) they are harder to find and usually cost $30-$50.