I came across an interesting problem last night with my Miller Mig gun. It has been giving me trouble quite a bit. Often the trigger didn’t work causing the wire not to feed. I checked at the welder where the small plug screwed in below the where the cable went into the panel by crossing 2 of the 4 sockets (where they were metal) with a pair of small needle nose pliers. The wire fed so I figured that it was at the gun.
I pushed out the pin to the trigger and out came the trigger and a small spring from underneath it. I was also able to take the handle apart by pulling off the lower “cap or cup” at the bottom. Inside there are 2 metal tabs that have points “contacts” on them so I cleaned them off. 1 of the connectors had come off so I tightened them both down by pinching the connectors with a pair of needle nose and then reconnecting. The gun still didn’t work.
Apparently, the tip at the center underneath of the trigger had worn down and was not making contact with the metal tab. I drilled a hole slightly smaller than the existing tab of the trigger and turned a small piece of nylon in my lathe and inserted it into the new hole on the trigger with just enough of it sticking out (about 3/16”) to make contact with the metal tab. It worked perfectly.
Should you all have any trouble with your Mig guns I’m sure that this is probably the problem and it is an easy fix.
Good luck.