My go kart is now fixed!!!! I went to Ace Hardware (an awesome store) and bought some new bolts for the wheel, and they worked like a charm. Only 1 out of 3 of the bolt holes was actually broken, and a long screw still screwed into it. It now runs again! The lawnmower batteries are running it now, and I hope to buy some new batteries soon to improve the speed. The pictures show the broken bolt hole. (sorry for the blurriness)