Troubleshoot the Chain
Confirm the chain is on the sprocket. Reposition for correct alignment. Read the manual for the procedure on loosening the guide bar.
Check the chain's tension for tightness on the guide bar. Adjust according to the manual. Usually you change the tension by removing the side case shield and then loosening two nuts on the guide bar with a wrench.
Observe the proper flow of oil lubricating the chain. Look for a plugged oil hole, dirty strainer or plugged vent on the oil cap, and clean to correct the problem. Check the oil level and adjust the oiler accordingly.
Look along the guide bar for pinched or wide bar grooves, uneven rails and burrs. Replace or repair the bar for proper chain movement.
Verify that the chain brake works. Sometimes the brake remains engaged.
Clean wood chips and debris caught in the guide bar groove and socket. Use a putty knife or wire and move the debris away from the nose toward the base.
Inspect the chain for low depth gauges, cutter damage and dullness. Replace or repair as needed.
Troubleshoot the Engine
Read the manual for correct starting directions. Starting problems usually involve minor adjustments, incorrect gas settings, flooded engines or a faulty ignition switch or clutch.
Look for low fuel or aged gasoline. Fill the tank with fresh gas, and clean the vent on the fuel tank.
Remove the spark plug with a plug socket to inspect wear and grime. Replace or clean the plug and reattach the plug wire. Take the old plug or product number to any home and garden shop that sells chain saws.
Inspect the air cleaner for dirt and debris. This problem can cause the engine to die or create uneven acceleration. Clean or replace according to the manual.
Adjust the carburetor as needed. Typically, the turn of a screwdriver can adjust the setting located on the carburetor. Proper air and gas mixture corrects this problem. Read the manual for carburetor access and settings.