I have a B&S engine (10T502-0457-B1) that when I pull it a couples of times it seems ok but then when I go to pull it again it will violently snatch the pull rope back. I checked the flywheel key and it seems to be fine. What else would possibly cause this reaction. Any help would be appreciated, If I get it to start it will run but it will pop every now and then. Hope you guys can help. Thanks.