This is an old thread but yeah the poulan,ryobi,husqvarna carbs need the special tool to adjust them which can be had on amazon or ebay. The first first carb that I tried to adjust which had the recessed splined screws got removed and took a dremel cutoff wheel and cutoff the aluminum housing around the screws then put slots in the top of them. Saved about ten dollars from buying the tool or around twenty dollars if taken to a repair shop. I have since purchased the splined tool which is commonly called the poulan splined carb tool(#530035560). FYI- The pacman tool is part#308535003, the double D tool is part #308535002.And the single D tool is part #308535001. Save yourself some money and adjust your own carb, there are plenty of videos on youtube that go into detail.