WARNING: This page is about a different car, the 2014 Mitsubishi Outlander. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Snap Ring Tapper Part
Courtesy of MITSUBISHI MOTOR SALES OF AMERICA.
Using a special tool, as when removing the nut, secure the armature and tighten the self-locking nut.