A DC brush motor is a type of DC motor that uses brushes and commutators to switch the current to the coils. To maintain and repair a DC brush motor, you need to regularly check and replace the brushes and commutators, as they wear out over time. You also need to clean the dust and debris from the motor, as they can cause friction and heat generation. You can use a multimeter to test the continuity and resistance of the coils and wires.