A spring-loaded clip holds the brush against the commutator on the armature or “rotor”. This is one of two brushes – the other is on the opposite side.
Pull the crank housing off the end of the armature. It’s a tight press fit where the bushing goes in.
This is the armature assembly. Electricity flows through a pair of brushes that ride against the commutator – which transfers power to the windings. Brushes are necessary because the armature spins so you can’t hard-wire the connection.
The armature assembly is on the left and the crank housing is on the right. The end of the armature shaft is machined off-center so when the motor spins the drive bearing moves eccentrically – causing it to press one way and then the other against a pair of arms. The arms are connected to the spindle. When the arms move from side-to-side, the spindle does too - one oscillation for each revolution of the motor.