I am following through the wiki and the bed design looks a bit updated from the documentation. Both the top and bottom plates have these four holes present, is there something that should be included in its assembly? I've run through the wiki and did a search on the forums but didn't find anything.
There are screws that go through there.... The bottom plate has spots etched out for hex nuts to hole the screws put in from the top plate... It is detailed here: http://wiki.e3d-online.com/wiki/BigBox_Printer_Sub-assemblies#.2810.29_Z-Axis_Bed_Assembly 14th step (or 6th step from (11) Z-Axis Drag Chain Assembly)
I think they decided it was redundant and the bigger cause of z-issues was the rods, which is why they had them ground to a slightly smaller diameter.
I thought I read Greg's post on G+ that they recommended the part but it wasn't included. I just printed my own.