zero crossover motor stutter at low RPM

wvmarle:
Tthe moment you set that direction switch in the off position (your drawing indicates it has this) that diode doesn't do anything as it's on the wrong side of the switch. Besides, your control electronics are AC side.

so it should be fine then? because if the direction switch is off then the motor becomes isolated from the circuit anyway. also the direction would never be changed while the motor is spinning.