Attached chart is helpful for determining malfunction in a motor speed controller based on its expected values for the trigger wires & motor output. Note that the color coding and terminals can vary depending on system model & generation. Refer to a wiring diagram to confirm your setup.
See https://katadyngroup.ladesk.com/663942-DC-Motor-Speed-Controller-Troubleshooting & https://katadyngroup.ladesk.com/063917-Adjusting-the-DC-Motor-Speed-Controller for further details.
NP, CT Connect System
NP400 MK2 MPC System