Check the accelerator pump for operation, if he went down on the throttle side the pump cam could be bent, not much of a thing....it resides behind the throttle cable wheel (on the throttle shaft), pushes on a lever, which in turn pushes the plunger.
http://www.partsforscooters.com/Carb...&category=468#
I am told the standard pilot jet is a 35 with a 38 being the replacement. (it's a hard call)....they run these things lean (at an idle) to pass emissions, and cover up the effects of lean with an accelerator pump. If I found I could control the idle mixture with the air screw, I'm not too sure I would be hasty to change the pilot jet, of course that kind of goes out the window if the accelerator pump isn't working/working properly.