Caution must be taken when replacing the gears! The main spline gear shaft is keyed at the bottom in a D shape, this shaft must go into the potentiometer just right because the potentiometer is also keyed in a D shape. The potentiometer is mounted below the bearing that the spline shaft goes into. If the shaft doesn't get lined up with the potentiometer before pressing the shaft down, you will damage the potentiometer.
*Any damage caused to servo from user incorrectly installing gears will void warranty.