@ MONO PRICE P/N 34437/34438 en 0202020200 % %o @ First use the included 2.5mm Hex Wrench and 4 of the M5x20 Screws (2 on each side of the printer), to attach the vertical Z-Axis gantry assembly to the base. In order to remove the screw rod that is attached to the left frame rail underneath the bed; you will need to use the 25mm Hex Wrench to loosen the screw furthest to the front of the printer above the wiring shames. Once the screw rod is removed, tighten back down the screw.