Z axis w/lead screw stuttering and won't move

My z axis on shapeoko 3xl is stuttering and vibrating during intitializing, but never moves. I switched out leads with x axis, and the motor turns, so it must be the z motor. Also unhooked 4 screws, and manually twisted motor, which turned screw, and carriage moved, so I assume screw is not in a bind at the bottom. Do I have to replace screw and motor? how do I remove screw from motor? must need special tool?

The leadscrew on the motor on the Z-Plus is integrated and not removable.

Are the linear blocks and rails lubricated?

https://my.carbide3d.com/docs/maintenance/

Let us know at support@carbide3d.com

They probably need lubricant. Should the lead screw turn by hand when ni power to motor?

Yes but it is awkward. You won’t turn it fast. Lube the rails with Mobil Vactra #2. Also lube bearing blocks. Find maintenance guide on forum.