Problem with stepper motor?

[leon22]

Hello everyone,
I'm currently building a gantry milling machine. For this I purchased 3 NEMA 23 stepper motors and a controller based on TB6560 on oyostepper.
Now that I have all three motors connected, I noticed that one of the motors is behaving strangely:
When starting slowly, it bounces back and forth before starting to run normally. However, which direction it turns is accidental.
The other two engines run absolutely problem-free. I then swapped the motors and the control crosswise, but the behavior of the motor in question remains the same.
I can therefore rule out a control error. A measurement of the resistance of the connected windings showed approx. 1.6 ohms for all motors.
So the windings are apparently OK.
The only way I can explain this is that the windings in the supposedly defective motor are somehow wired incorrectly. As I said, the engines are brand new.
Has anyone ever had something similar?
Thanks in advance

[alan254]

ck the grubber screws on the shaft.