Update-- I was able to get both of mine going. The fix in my case was to remove the reel deck cover (the flat panel right under the take up and supply reels) and remove/clean/lubricate the pendulum arm (in particular). I also cleaned/lubed the rest of the gears under there, but the pendulum arm...
Hah! Good timing!
I happen to be working through the exact same issue, albeit on a couple of SLV-R5UC decks. The decks had a litany of other problems (power supplies and audio boards failed due to the leaking Elna electrolytic caps), so I'm just now trying to suss out what's going on...
