"Right," Ed said with a nod. "Push it into the port, and then tighten that screw the best you can," Ed said, pointing to the spot that needed to be tightened. "It will spark at the socket when you push it in, and that means you've got it."
It was strange to be explaining this to someone else when he really didn't understand it that well himself. Winry made her own automail and mechanics, while using the same basic concepts, often added their own flair to their work. Ed wasn't even entirely sure why it sparked. He was usually too caught up in the electric sharp pain of his nerves reconnecting with the metal. He didn't warn her about that part, because it didn't seem relevant to let her know that this was going to be painful for him.
He took a deep breath and tried to relax, knowing it would help -- but not much.
"Let me know when you're going to do it," he tacked on at the end. Winry had caught him off guard far too many times.