The holes in the Z-axis motor mount are slotted to allow adjustment. This will be performed at a later step. For now, push the motor as far back (towards the frame) as possible and fasten all four M3x18 screws
Take care not to over tighten the M3x18 screws as you can damage the printed parts
Install the axial thrust bearing over the shaft of the stepper motor. It should sit within the pillow_block printed part
Spider Coupler
Apply downwards pressure on the spider coupler to compress the axial thrust bearing
Tighten the lower screw on the spider coupler whilst applying downwards force as stated above