I contacted a company that repairs miller welders and the tech felt that the problem was with the rectifier or to be more specific the diodes. Not wanting to haul the welder to their shop I tested the diodes in mine and they were all ok. After spending some time looking at the wiring diagram I'm not sure why the tech thought that the rectifier was the problem since my problem is when the machine is in AC and that does not appear to me to be affected by the rectifier or diodes.
Tags: AC, Al, Arc, DC, Econotig, Fine, Miller, operates, try, Weld, welder