I bought two of these 125D ATV's for my kids for Christmas and one of them is leaking oil out of the front of the motor. The screw seems to be stripped or something as it will not tighten and will not come out it just turns and turns. There is some play in the screw when you move it a bit side to side the other 3 screws are solid. What are my options for repairing this for my son? Any and all assistance is greatly appreciated.

Oil is leaking from the screw that is closest in this pic. Bottom left screw if you are standing in front of the atv.