Check the chain tension. Release the chain brake by pulling the front hand guard back toward the front handle. With your left hand on the top of the front handle, use your right hand to grab the chain on the top of the bar. Attempt to rotate the chain. It should spin freely and no slack should be seen in the chain on the underside of the bar.
Loosen the two bar nuts one full turn, using the wrench end of the combo wrench or 1/2-inch socket.
Use the screwdriver end of the combo wrench or the flathead screwdriver to turn the chain tensioner screw on the front of the saw -- clockwise to increase the tension, counterclockwise to reduce the tension. When properly tensioned, the chain should rest snugly against the underside of the bar with no visible slack.
Hold the bar tip up with your right hand and use the wrench end of the combo wrench or 1/2-inch socket to tighten the two bar nuts.