Well it has arrived. I am impressed by Japanese sellers . Seven days on the button to get to Oz. I have experienced that organisation and good service with other Japanese sellers. No wonder I like them. What's more, the lens looks much much cleaner than shown in the eBay advert. The seller made it sound (and somehow look) somewhat worse than it actually is. There is a smudge of something on an inner element (I have not yet studied it closely but will soon) but its pretty minimal - so I may defer any thoughts of stripping down and cleaning for now.
Excellent news. 🙂 Although if you do decide to open it up, it's a pretty simple DIY.