On this parts fiche the Spring-brush is the most specified component.
Parts such as the Starter Motor: Washer-spring,6mm, Ring-o,starter Motor, Spacer,connecting Rod, Bolt are included in the Er650eff Er6n 2015 Europe,middle East,africa Starter Motor parts fiche.
The component with the lowest price in the STARTER MOTOR schematic is the Washer-spring,6mm.