Hello Illuminarti & EldRick
The niose I am hearing is air turbulence noise not bearing noise. The fan is installed to suck from the back of the printer so the air get pushed forward to the front of the printer passing over the heat sink. Take a look from the front of the extuder and you will note that there is only 2 hole that the air can move through without obstruction. If you place a small bit of paper in front of the extruder and note the air flow then remove the screws and move the fan backwards you will see the improvement in air flow and hear the reduction in noise.
The venkel's fan duct looks nice but I am working with the fan at the back of the extruder not the 2 fans at the side I think these fans are for PLA cooling, I tend to work in ABS. The side fans do not run 24/7 like the rear fan.
I have put this design up https://www.youmagine.com/designs/ultimaker-2-extruder-fan-mod the two holes on the wings are for the the long screws (that hold the extruder together) and the othe 2 smaller hole are for the fan mounts (I added 2 blind hole so you can dill them out if you can find some extra scews for the fan) this is a quick and dirty design and works well when printed for my old Solidoodle (setup for small part manufature), you may need to change it a bit to print well on your printer maybe change the wall thickness (I have a smaller nozzel of 0.3mm).
If you think this maybe the right way to go I will cleanup the design. It was made with sketchup on my laptop while watching the Sydney City to Surf rush it way past my balcony, as I drank coffee and the speakers blasted out "running on empty" to help get the runners up the first hill, it took a number of hours to get the 85,000 runers up that hill and it was the easy hill.
Now to work on the filiment jamming in the teflon tube it seem tight after the exruder gear changes the shape of the filiment (little lumps and bumps that the teeth make).