04 | Z and X Axis Assembly - iFixit Repair Guide

What you need

Insert the Misumi LM8UU bearings to the x axis motor holder. Use 2 x M3x10 socket Cap Screws and 2 x M3 Nylon Nuts to squeeze the bearing holder. Do not tighten it too much, just to keep the bearing in place. Not more.
Warning, bearing tightener nuts are NYLON M3 Nuts, not the regular nuts.
Put the POM Nut in its place and align the unthreaded holes. Use 2 x M3x18 Socket Cap Screws and 2 x M3 Nuts to fasten the pom nut.
Push the GT2 Pulley to the motor shaft but to not fully tighten the small screws on the pulley yet.
Use 3 x M3x18 Socket Cap Screws and 2 x M3 Nuts to fasten the pom nut.
Insert 2 x M3 Square Nuts to the motor holder body and 1 x M3 Square Nut to the cable guide body.
Use a M3x0.6 Flat Head Screw to mount the X motor cable guide housing.
After installing the X motor cable through the guide channel, use a M3x12 Socket Cap Screw for the upper hole and a M3x18 Socket Cap Screw for the bottom hole to mount the X motor cable guide cover.

Insert 2 xLMU8 Bearings. Use 2 x Nylon M3 Nuts and M3x10 Socket Cap Screws to tighten the bearings just to hold the bearings in their place. Attention! DO NOT TIGHTEN more!
Put the Pom Nut and align the unthreaded holes for the screws. Use 2 x M3 Nuts (See the small picture at left-bottom to insert one of the M3 Nuts) and 2 x M3x18 Socket Cap Screws to fasten the Pom Nut in it's place.
Insert 2 x Nylon M3 Nuts from top and bottom to fasten rod spacers. Use 2 x M3 Washers and M3x10 Socket Cap Screws to tighten later in order to take up the excessive space between rods and the X axis holders.
Insert 2 x Nylon M3 Nuts to the belt tensioner.
Push the Idler Timing Pulley inside the belt tensioner.
Use the supplied Dowel Pin to secure the Idler Pulley.
Use 2 x M3 Washers and 2 x M3x20 Socket Cap Screws to mount the belt tensioner. Catch the M3 nuts in the tensioner, and tighten the M3 screws up to the celearance of the tensioner.