I agree with this. The Red and Black would go directly to the DC motor and the White/Blue/Grey would go to the three terminals of the feedback potentiometer.
Measure the resistance between White/Blue, Blue/Grey and White/Grey. If the two smallest values add up to the largest value it is a potentiometer. The pair with the highest resistance are +5 and Gnd and you read the position from the third wire with analogRead(). You can then use a DC motor controller (H-Bridge) to steer by running the motor to match the feedback value with the desired value.