After edging around beds for a minute or so (trimmer upside down.) When turning it back to proper trimming form right side up the engine will hesitate as if its getting no fuel...inbetween that time if you hit the gas it will die. For the 2-3 seconds the engine is hesitating after being turned back over you cant hit the gas at all. What gives? Air in fuel lines from turning it over ???? any ideas? its brand new.