Great little guide.
This picture explains my problem. The mirror part dangling below there came loose on mine WITH the white plastic part STILL attached to it. Your guide clearly states to remove that red screw assembly to remove the white plastic except mine just came clean off so I have no idea how the hell that happened. Regardless, one of the white prongs on the back of that white plastic bit snapped off this morning (probably because of the cold). So I'm buying a used mirror and going to replace the white plastic as all other parts seem to work fine on mine.
Cheers for those pics and the guide, very helpful.