I'm fairly sure that the iPF6xx0 uses an entirely separate cutter/rail design instead of the bigger iPFs' self-serviceable cutter-on-head design as shown in 35.marco's video.
Unfortunately, that part for the iPF6xx0 does not seem to be easily available online. I have not called Canon, so I don't know how available they are direct from them. If you find out, please let everyone know.
My plan, if/when my cutter wears out and there isn't an easy replacement, is to design something custom around any of a number of circular razor blades on the market, and 3D-print it.