How to test the hall sensors?

In order to test the sensors you need to apply +5V (using power supply or battery) between the red wire which is te "+" hall sensor wire and the black wire which is "-" hall sensor wire and check the voltage between each of the hall signal wires (white wires) to the red wire (with multimeter) - while you rotate the motor by hand the voltage should change between +5V to 0V, that's how you will know if the halls failed or not.
BTW you can use up to 30V for this testing. (we use the SS411 or S41F sensors in our motors).