Wanhao i3 Rear Filament Feed Guide

Due to a reconfiguration of my workshop, I had to locate my filament spool "behind" my Wanhao i3 (i.e. next to the Y axis motor), and feed the filament over the drag chain and into the extruder from the rear, so to speak. This caused the filament to rub across the drag chain and wires, which wasn't desirable. This mod, which attaches using two M3 screws through the drag-chain mounting points, alleviates that rubbing.