I am trying to figure out what he stopped leaking with teflon tape on the thread. Maybe his cable was still full of oil and slowly leaking back out. The tape stopped that from leaking. He probably didn't clean the cable, while he was doing the seals.
A little bit of trivia: When I ordered the o-rings they quoted two parts numbers for the speedo and striking rod, but when I measured them on a o-ring cone, I came up with the same size. There is a photo of them in the "Leaky transmission" link.
My rubber hat washer is long gone. I think the PO left it out when he installed the close ratio. I cut a ring out of 2mm NBR sheet with some hole punches. Its main purpose is to keep dust, grime and water from getting in. It probably would stop oil leaking if the outer cable was in good condition, but that is not its intended purpose. And like chickman said, only available with a new "genuine" inner cable and the better aftermarket units.