I have an older three phase miller itg welder. I replaced the conactor and got everything going. I put the lid back on and now if you put the clamp on the table it arcs out and the high frequency start wont come on. if you put the clamp in the air and the metal your working with it will weld normaly. the clamp arcs to the floor, rods and table arc to the case of the welder. what could cause this? im going to pull the lid off again and test.