Put the grease gun nozzle on the center of each rear tire, which is located on the outside of the tires. Pump the grease gun handle until grease begins to squirt out, around the rear axle of the MTD rider. Locate the gear case on the rear axle and unscrew the bottom bolt with the crescent wrench. Unscrew the bolt from the top of the gear case. Put the funnel in the hole and fill the case to within a 1/4 inch form the top. Remove the funnel and screw the top plug back in.