I hope someone can help me. I have changed the polarity on my welder but I have found that when I press the trigger the wire feed motor does not work. Having looked in the torch it seems the trigger connects to the now negative torch wire. Does this go to the wire feed motor? Maybe the motor is not working because the polarity has changed. Is this right and what do I do to fix it? The welder is old about 25 years but still works well so I am reluctant to buy another one.