Bought an estate sale Necchi

Question

Bought an estate sale Necchi with this number 48301/also has a bc/made in Italy. No other model numbers could be located. It has a three prong hook up. My problem is that all the wires that connect to the back of the prong are all disconnected along with the wires to the light. The prong itself has numbers 1-2-3 were the connection are retain by plastic s***w on nuts. I tried different ways to figure out what sequence they go, but no luck. Hope you can help!