Ran well most of this season but now surges. Replaced fuel filters, cleaned the carb, seems to have too much air. With my thumb covering 1/2 of the air intake to the carb it runs smooth. It does run smooth at highest speed but cuts out at 1/2 throttle. Dealer will ultrasonically clean the carb for me but I had it off and thought I cleaned it pretty well already. Any suggestions?
Also where is the serial number?
