Ah, yea that;s the one way bearing slipping on the starter shaft.. You can remove and clean it and it may work for a while, but in my experience, the best thing is to preheat the motor with a heatgun or hairdryer, and point it at the pull starter for about 10 seconds while your at it.. The heat seems to do something to the one way bb that makes it grab?? (Ever notice how it works fine after you've had the motor running a while?) same principle.. But preheating the engine has many benefits! Makes it start alot easier/faster, and helps the longevity of the engines health! It's a win win!! Good luck!