In addition, note that the common lead in this type of motor is usually white or purple. If there are additional leads in the run widing group, continue to use the ohmmeter to test the now-identified common and additional leads. Descending resistance will give you ascending speeds.
If you are confused by me saying that the current flows from positive to negative, that just happens to be a historical convention. People like Benjamin Franklin, who helped figure out the mystery of electricity back in the 18th century, believed it was a flow of positive charges, so it flowed from positive to negative. We call this idea conventional current and still use it to this day in things like Fleming Left-Hand Rule.
The shield strongly attenuates the electric field noise. Core to shield capacitance is added to the stray capacitance, increasing ground currents in the loop. These currents generate a magnetic field. It is important to minimize the area of this loop as far as possible by routing the cable close to grounded metalwork.
Shield drain wire must be spliced only to mating shield drain wires and not grounded at the junction box. Feedback shields must be passed through pin for pin. Separate junction boxes for power and feedback are required.