Speaking of that little jet that sits on top of the extension tube (the jet needle), do you happen to know which way it's properly oriented? I think it's with the smaller hole facing 'down' towards the extension tube and the larger hole facing 'up' toward the needle jet and the diaphragm slider.
Edit: Checked the FSM. It says to insert the end with the smaller diameter facing 'up' once the carb is oriented as it would be on the bike. As such, my assumption above is correct. Also, it doesn't fit properly the other way