The settings are:
H one turn out from bottoming
L one and one quarter turn from bottom
Replace your fuel filter in the tank as well and make sure that fuel is getting to the carby first before you continue to tune the carby.
Once the machine starts then move the throttle quickly and if it does not hesitate then adjust The H screw till it peeks out then back off one eighth of a turn.
Regards,
Bruce
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Commercial Outdoor Power Equipment P/L.
Ph: +61 2 9713 4699
Fax: +61 2 9713 4915