[LotusSevenMan]

Hi all.
 Well I tried several sizes of bar held in place with a mixture of tightly wrapped elastic bands as per your pic Tom but in the end I found the best extension device was a washer that was about an 1/8" wider either side of the knurled head. Larger just made it trickier to turn in large gloves which I found strange. The suitable washer was a fairly tight fit into the flat blade slot on the tickover screw. I filed a flat on it first to make sure it had maximum adhesion area then JB WELDed it into place. Anyway, after the experimentation I went with the above and........................

Easy?

You bet!!!
Seems to work really well and very easy to turn with a gloved hand too. Just gives that bit of extra leverage so you can set it turned in a bit at start up and then reset it on-the-run if required. 



PS The hole in the middle is actually a device to reduce wind resistance and save weight (ahem  )