Instructions
Ensure there is actually power being provided to the welder, if you notice there is no wire feed, weld output, gas flow or fan operation. This means checking the power switch is set to "On" and checking the circuit breaker has not tripped. If it has, then reset it.
Check the contact tip and cable liner for any clogs, which may be affecting normal use. These clogs are often responsible for a lack of wire feed when you pull the trigger, despite gas flowing and the fan seeming to operate.
Inspect the welder for any leaks, which may indicate broken seals or faulty wiring. This is particularly common where the gun connects to the machine. Have the appropriate seals replaced by an expert.
Make sure the weld gun is structurally sound. Even the smallest crack can be responsible for an unstable weld arc.