1. Pull the yellow plastic caps out of the carb adjusters.
2. Lightly seat both of the carb adjustment screws.
3. The left screw, the "low" idle adjustment should be turrned out 1 1/8 turns.
4. The right screw, the "high" idle adjustment should be turned out between 5/8 and 3/4 turns.
Adjust from there....
I like to leave the cap on the auger and find myself a big pile of snow. That way I can run the thing, at idle and wide open and everywhere in between without digging a hole or harming the blade etc...
I also prefer doing this with two people, one person to hold the auger and one person to set the fine tuning on the carb.
So, have one person start up the auger. The idle should be fairly strong. If it's not, open up the left screw a bit... If you turn it too much the engine will stall. Then have the other person gun the throttle. If the engine chokes, turn out the right screw a "c" hair and try again. You want to be able to go from idle to full on with no hesitation.
If worse comes to worse, I live in the Worcester area... lol.