Qu-Bd Extruder spring plate
See updated part http://www.thingiverse.com/thing:279192
This is part V as labeled in jeepguys assembly instructions. It is what the spring and washer sits on to apply pressure to the filament.
I found that the center slot for the long bolt HW04 was too narrow and would bind up. I suspect this would give intermittent feed issues. This part was made to widen that slot.