So I'm cleaning the carbs on my o4 V Star 650 and I removed whats referred to as "Main jet screw", page 206, # 18 in my Clymer manual. Well now I am having a problem reinstalling it. The screw is hex head with threads however there are no threads in the port it goes into. There's a small pin through the left wall of the port that protrudes into the opening. I'm guessing that this pin may be what holds the main jet screw in place. Any information would be helpful. Thanks.