Z stepper just vibrating and making noise

all of a sudden my second z stepper mottor doesnt turn. It just shakes left and right a few mm and then just buzzez. What could be causing that i didnt change anything. I tried a different stepper that isnt hooked up to anything and it does the same thing even with no load on it. Any ideas? im stuck.

Is your x axis level? I’ve had similar issues if either side gets out of level. With the power off you can move either z screw by hand to get the rail even on both sides

As Korwen mentioned, check if your x-axis is level. When the x-axis is out of level, the z-nuts can bind the z-axis lead screw(s) enough to stop the stepper motor(s) from turning. They will just sit there and “buzz”, quite loudly.

However, you mention that you connected another stepper motor to the wiring harness for the malfunctioning stepper and got the same buzzing and non-rotation. So it would seem that it is not the stepper but perhaps the wiring harness or connector. Worse case scenario is the stepper driver on the controller board is not working. I’m out of my depth when it comes to this.