I rebuilt the updraft carb on my snowblower yesterday. Done many carbs, this was the first updraft I can remember. The main jet is a brass tube that goes diagonally across from the lower section to the upper. You need to remove the jet before pulling the sections apart and need to hold off on reinstalling the jet until you have the top and bottom section loosely screwed together. The brass jet tube needs to find its way without everything being screwed down tight.