I'm using the standard ceramic (pink) gas shields, pure tungsten (for steel) and DC neg. Yes it does do it on AC occasionally when I'm doing aluminum, but not as bad. I can finish a short weld, pause, and when I start again, it does the same thing, so I know the gas is there. Also, my unit does a pr...

Just recently when I start tigging the "flame" shoots out of the cup, on the inside diameter, and not from the tungsten unless I rapidly increase the amps. This happens with new cups and new electrodes, no matter what size. My machine is a Lincoln (stick/tig), sq wave, 175 amp, PRO. Argon ...