Pictured is the Steam Controller with the new trigger mounts installed.

Replace the new mounts onto the respective corner of the back of the printed circuit board, and while it's laid flat, tighten a screw into the corner through the mount and the printed circuit board to hold the trigger assembly in place.

Start laying the top of the printed circuit board back onto the front of the controller, and reattach the trackpad ribbon cables carefully.

Ensure that the button mesh and the release lever popper at the bottom are laid in place.

Lift up the top of the circuit board, and replace the USB port cover two-piece over the top of the printed circuit. Ensure that it goes over the bumper levers of the trigger mounts, and that the micro USB port is flush.

Replace the four T6 screws attached to the trigger mounts and the back of the PCB through the front chassis.