Ok, I checked Wikki and the Technical Docs (as well as Search), but could find any reference to the speedo cable.
So here goes..
My speedo needle wobbles on acceleration until about 40mph, then it becomes smooth. Here at work, with Daisy at home.. I remembered that the dood I bought the bike from just had the front tyre replaced as he had a puncture. Does the speedo cable have to be detached to remove the front tyre/wheel?. If so, the cause of my issue could be that the shop did not re-attach the cable correctly (and maybe did not apply any lube).
What do the experts think? Bike has just under 2k miles.