You can adjust it running. Start it, and loosen the lock nut. If the adjuster is free, it will immediately sound like a bucket of bolts rattling around in the head. Turn the adjuster screw counterclockwise to tighten the cam chain until the rattling goes away. If it whirs or whines, it's too tight. You'll hear it. Just adjust it until the rattling goes away but not any tighter, and tighten up the lock nut.