Some small bits broke off the case and fell into the interior of the system. While cleaning up the mess, I notice three of these special metal brackets on the base of the case. I know two fit inside special grooves on the left and right side but the third one (show in the center of the photo below) has me perplexed. I don't have another system to to which I can compare. Videos and guides I've seen leave out detailed photos or gloss over these metal brackets because it seems pretty obvious where the two go.
Any idea where the third metal bracket goes? Pics are immensely helpful.
Click to enlarge photo:
