The MAXPlanetary Base Kit comes with a MAXPlanetary CIM/Falcon Spacer (REV-21-2119) to ensure that the input stage for CIM, MiniCIM, and Falcon 500 motors sits correctly in the MAXPlanetary Gearbox. Please be sure to install the spacer before assembling your MAXPlanetary Gearbox and attaching the Input Stage to your motor.