I picked up an old Miller 35S mig/spot welder. It's in good condition and seems to weld ok as far as I can get. It came with a bottle of gas but I can not identify it. It is like greenish/turqoise in color but unlabeled . Is there a way to ID it in the stampings? Secondly, the weld weld lays out decent but I don't think it's getting all the gas or maybe any gas. The regulator was wrong so I changed that. I want to know the proper way to test the solenoid for the gas as I can not hear the gas. The weld isn't neccessarily porous but it is dark gray versus the shiny/light gray u typically get with c25 mig. Is it possible that this is just co2 gas? Usually I can hear the gas and I can't now. I used co2 all the time with 777 wire but never with solid wire. Thanks if u can help. Dave