[dsraven]

So the welder, I assume it's a mig with gas hooked up? If you shut off the gas bottle the noise stops? Or does It only make noise when you pull the trigger to weld? Can you tell if it is making the noise inside the welder's metal box or somewhere else?
From what I recall the tank supplies gas to a solenoid valve which only allows gas flow when you pull the weld trigger. Then gas flows from the solenoid out through the mig hose to the tip.
Anyway, hopefully you can fix it cheaper than buying a new one.