Michael -
First, glad its working, our older vehicles are supposed to be fun!

As to the issue you corrected, my "SWAG" is as follows:
Remember the conversation we had concerning the idle tube and how it seals? For those who weren't listening to that conversation

, Carter stated to ALWAYS replace the idle tube when rebuilding a W-1. This for several reasons (one, Carter wanted to sell idle tubes); but also because reusing an original idle tube WITHOUT MODIFICATION would give issues. The reason is that the upper end of the idle tube is inserted into a tapered passage. When the tube is rotated (because of the screw plug), the tube is compressed and forms a seal. Reusing the old tube without modification will not form the seal. However, the old tube may be reused if the rebuilder reforms the outer diameter of the upper end of the tube. This may be done by CAREFULLY rolling the point of an icepick inside the upper end of the tube. This will expand the outer diameter, so the tube can again seal when inserted in the tapered passageway. And no damage will be done to the calibration, as the calibration is in the bottom of the tube.
And always remember the ABC's of carburetion: (A)lways (B)uy (C)arter

Jon.