I purchased a like new used 6 times ( and it shows clean inside and out ) 140c mig welder . it has the 100L gun head unit on it . all went well except for the shield gas hardly comes out the end of the nozzle . and yes I have welded for years / I know to check the basics . full new bottle of 75/25 mix gas . reg flow set at 20 to start then 25 and still no difference. I took the gun lead out of the body of the welder to check the O-rings and also for flow from the machine . all is good and no objects blocking the flow. I also took the set screw loose and removed the inlet nozzle tip for the wire . I did notice the inner linner core was not seated up to the tip base . also with tip seated and set screw locked down its a pita to start the wire like its droping from the inlet tip before it goes in the liner . so I took the gun head all apart down to the linner its self . no blockage I could fine. so all back together and lid up on the side of the welder and trying the trigger and I could hear a TON of gas movement next to the gun inlet tip at the wire guied / drive wheel area. in my opinion the gas is not getting sealed in to the gun linner or its missing a part to seal it up and make it go down the liner . any input would be super thanks .