Adjusting the carb on a Craftsman leaf blower is relatively easy. You'll want to buy a carburetor rebuilding kit (which is inexpensive), thoroughly clean all of the non-replaceable parts of the carburetor and replace other parts.
All in all the process should take about an hour and when you are finished your craftsman leaf blower should run as good as new.
How to Adjust a Carb on Craftsman Leaf Blower
Turn the adjusting screw on the side of the carb while the engine is running until the engine is running at peak performance. Turning the adjustment screw to either the right or the left (no more than half a turn at a time!) will either increase or decrease the air flow through the carburetor and will either make your fuel mixture leaner or richer. Sometimes (though not often) this is all the adjustment that your blower will require.
Buy a carburetor rebuilding kit from Sears or from another source. The kit must be made especially for your make and model of leaf blower. Be certain that you have the Model Number of your particular leaf blower before you try to buy your rebuild kit. A carburetor rebuild kit for a Craftsman leaf blower is under $10 when purchased directly from Sears.
Disconnect the fuel line from the carburetor. Depending on the model of leaf blower you have this could mean unscrewing a clamp with your screwdriver or un-pinching a clamp with your pliers. Have a small glass container ready in which to drain any gasoline.
Remove the screws holding your carb to the leaf blower. In most models there is only one screw to remove. Set the carb on a clean working surface and carefully disassemble. Make mental or written notes of how each part is connected as you lay out the parts for cleaning or replacement. On the right side of the carb will be a small screen-this is most likely the source of your trouble so handle it with care. Fill your small cleaning container with Gunk or another carburetor cleaning solution and put the screen and any other hard parts which appear dirty into the Gunk.
Clean the screen. Use your brush to make certain that the screen is completely clean. Use your brush to clean the carb idle plate and any other parts, but make special care to clean the screen. Discard the old gaskets.
Place the new gaskets that come in the carb repair kit in place. Use your finger to spread a thin layer of oil on the surface of the gasket before you remount the carb. If your repair kit comes with a new screen you may with to use the new screen in place of the old one. Reassemble the parts of your carb and carefully set it back in place, being careful not to damage the new gasket. Screw the carburetor back onto your leaf blower. Reconnect the fuel line. Full the gas tank and push the bulb to prime the carburetor. Start the engine. If it does not start after half a dozen tries then turn the chrome carb adjusting screw half a turn to the right and try again. If it still fails to start then turn it a complete turn to the left and try again. Your Craftsman leaf blower should now to running as good as new!