Items you need for this step:
Attach the 4 remaining v wheels to the spindle mount, as in the picture below: at one side, you’ll use the eccentric spacers to create a 9mm space between the wheels and the mount and at the other side, you’ll use the normal spacers.
At the side where you’ll use the eccentric spacers, you can also use M5 flat washers between the aluminium of the spindle mount, and the nylon insert lock nuts if you like.
Attach M4 screws – do not tighten yet (the spindle still needs to fit in):
And attach the spindle mount to the ACME delrin nut with M5 16mm button head screws