YOu need to clean the one way bearing. Take the pull start off carefully making sure the insides don't stay on the pullstart shaft or else the spring will pop out. take the bearing out of the pull starter and get some carb cleaner and spray the beaing off to clean the oil off of the needle bearings inside of it. THen clean the pullstart shaft and take some sand paper adn scuff the shaft up a tiny bit so the bearing has something to grab.