There's a simplified schematic on top of the drawer that signifies each section (this being the FA section). It doesn't say much about each part (other than tube names, and adjustment areas)....more of a map than a true schematic.

Although, by looking at this I noticed that the 3rd cap in question is not a part of the FA section that we are dealing with.

I've attached 2 pics of the 2 caps, labelled accordingly.