I see that no one has responded to your final post. I just purchased a W&W D-9 and it has two felt pads, one on either side of the disks. My machine is pretty original so I would trust that they were supposed to be there. Mine got a dot of oil after a slight wiggle between layers of a paper towel.
The mention that the disks were riveted together helped me a lot! Not sure how it is supposed to help with tension but now I know NOT to try and get them apart.