I was given an XL2 for free recently (not running) and thought I would fix it up for a trim saw (beats my 039). I got it going and it seems to run great but wont idle. There are two screws showing on the carb. a larger one on top (when looking in from behind the saw) and a much smaller screw below. Does anyone know which is the idle screw and which way to turn to give me more idle?