Since it is new, I would find an authorized service repair center and let them fix it. Should be covered...
Best advice you can get!
Continuing down the "What to do 'til the doctor comes" route...
I still say something "happened" to dis-adjust that engine.
Check fuel filter located at the end of the fuel line in the tank. Line might be twisted into a kink stopping proper fuel flow.
"Glob/flake/speck/splash" of "something" get into the tank from your "new?" fuel container? That's happened before.
Check the air filter... like above post says it dosn't seem to have enough time on it to clog up but... Also make sure the mounting fastners haven't worked loose allowing dirt past the air cleaner. Some 2 strokes can be very sensitive to the air cleaner or lack of proper fit (leaned out mixture if filter is loose).
Pull out the spark plug and look closely at it. Oily-wet? = Definite carb mixture problem. Carbon or other "fouling" on the electrode gap? Wire completely ON the plug firmly? Proper gap..
Something loosened (carb or a gasket) allowing air into crankcase... (see a pro).
I think it should be a law that all OPE manuals give full instructions on setting both HI and LOW and Edle Speed settings. "Only one screw" just is plain silly for anyone including pros or casual users...
Keep us posted on the doin's! Tutorman, it may save somebody else's posterior down the road! Maybe even mine!