I have a 1950 3100 and recently upddated to a 12 volt system. But my choke doesn't close all the way when I pull the knob out.Closes slightly. What is the best way to adjust the set screw closed or open? The spring on the choke appears to be used for opening it after being closed is that right? I have laced the outer rods with WD 40 but doesnt seem to help much. I need ideas.