If you get the WeldCraft Q5W Dinse to convert a torch to work with the Powertig series, you will have to trim back the vinyl part of the red connector where the male end of the Dinse goes into the welder.
The vinyl part of it extends too far into the round cup on the face plate of the 250EX and will not allow the little nub on the male end to get close enough to the slot in the female connection on the welder. You will be pushing and cursing trying to get it inserted correctly and it just won't work.
The best way to trim it back is with a straight edge razor blade. Trim it back to almost the base of the dinse. The red vinyl went up to the base if the lower round area and prevented the dinse from inserting into the female connection.