Attach Side Components
Attach the two remaining side enclosure components using the two #6-32 x 3/4" machine screws, lock washers, and hex nuts.
If the rear panel mounting screws get tin the way, remove them. Reinstall once the bracket is secured.
Attach Top Brackets
Add the remaining four brackets to the top corners and secure each with two #6-32 x 3/4" machine screws, lock washers and hex nuts.