I purchased a used 2001 Yamaha Warrior, and the owner stated all it needed was a starter (friend of a friend type deal). I installed the starter and it turns over, however, during starting there is a loud knocking sound. The sound goes away after it starts. I removed the side cover to review the gears, and they all appear okay, with no missing teeth on the gears, and nothing visably loose. Any ideas? Appreciate any help.