Before reinstalling the mirror holder to the inner holder (A) of the actuator, check the actuator rods (B) and the actuator boots (C):
If each rod is off the actuator hole, insert it securely.
Each rod should be covered with a boot. If not, adjust the boot into the proper position.
Reconnect the mirror defogger connectors. If equipped, reconnect the automatic dimming mirror connector.
Reattach the hooks of the mirror holder to the actuator, then position the mirror holder on the actuator. Carefully push on the clip portions of the mirror holder until the mirror holder locks into place.