hey guys. im having trouble getting my diff together. the axle sprockets that stick out of the diff for the drive of the rear wheels doesn't fit properly. one side slots in nicely into the ball bearing but the other side doesn't fit. it's like tha sprocket is a touch too big to geth through the hole. is it a wrong part with teh car? or should i sand it down as there may be too much paint on it from the factory?