Morning Neil

No I haven't solved it as yet, the grub screws go through the face of the gear and the shaft it slides onto, so the holes are drilled, then tapped, half of each hole on each part so I suppose it is a kind of keyway, so when the grub screws are screwed in this would then be the keys to stop it from spinning on the shaft, I had a look at the photo you put on a few years ago and it does look like it was the same set up

Cheers

John.