just took delivery of a portamig 215 and am having problems firing it up. When connected to power and switched on the fan comes on but wire feed motor doesn't come on when torch switch pressed. Also no sign of any welding happening when wire placed close to an earthed piece of metal. I've taken torch off machine and tried joining the 2 contacts with a piece of wire as described in instruction and still wire feed motor doesn't work. Am I missing something obvious here or is there a problem with machine?