The nomenclature "42-40" is a standard stepper motor classification:
| Symptom | Likely Cause | Fix | | :--- | :--- | :--- | | | One coil is disconnected or wired wrong | Check continuity of Red/Blue and Green/Black. Swap wires. | | Motor is extremely hot (>100°C) | Vref/RMS current too high | Lower current in firmware or potentiometer. | | Layer shifts or missed steps | Motor current too low OR mechanical binding | Increase current 10%. Check belt tension and rail smoothness. | | Clicking sound on Z-axis | Motor holding torque insufficient for gantry weight | Increase Z-axis current slightly. Grease the leadscrew. | | Motor won't hold position | Dead driver or broken wire inside the sleeve | Swap motor with another axis to isolate fault. | Creality 42 40 Stepper Motor Datasheet