I was trying my 2016 250ex out today for the first time on tig and I put a 3/32 tungsten in the torch head. I happen to notice that the back cap that clamps the tungsten in place was not letting the O-ring seal against the torch body. The tungsten was clamping before the O-ring was inside the head. I had to chuck all the collets that came with the machine up in my lathe and cut about 3/32 of an inch off the back part of the collets. I ordered a gas lense kit from ebay and all the collets that came with that kit were already shorter so they would seal. Any of you that have been having trouble with shielding better look at the collets.