The 23KM-C051-09V datasheet notes that this motor has high inductance (5.7 mH). Use a driver with a high PWM switching frequency (≥ 20 kHz) to avoid audible noise and excess heating. Also, enable "automatic current reduction" (half-current when idle) to reduce case temperature.
Where would you find a 23KM-C051-09V?
Like all 1.8° steppers, the 23KM-C051-09V has a mid-range resonance zone around 200–300 full steps per second. Use microstepping (at least 1/8 step) or a damped coupling to prevent missed steps. 23km-c051-09v datasheet