argon and c02

How did you check the flow? Can you feel the gas and hear the gas coming out of the gun? Maybe the solenoid valve is stuck since the welder sat for so long.

 

I had a C25 bottle sitting idle for 3 or 4 years at one time and it worked fine when I was finally able to resume working.

If it's a gas issue, I'd first make sure you have 100# pressre or more and if you do, have the welder checked to make sure the gas is getting through to the nozzle.