Just picked up a old hobart 364 1DSCN3728.jpgDSCN3729.jpgDSCN3730.jpgDSCN3731.jpg. Got a few questions. there is a plug in the center of the amperage dial. what is it for? He gave me a pedal with 2 sets of wires sticking out. no plug. where do I get a plug and which one does it plug into? thanks for any help you can give.