Today's update...
The keyway in the axle was shot, the end of the hub shot too. The end to middle was ok and useable but needed a longer key to replace the small woodruff key.
So I ordered a 1/4" end mill and used the lathe to cut a new one.
Firstly making sure the height was spot on by marking the centre of the axle, this needs shims in order to get the correct centre. The final score line can just be seen.
Then running the mill through in small passes to cut an 3 inch keyway.
Once the full cut was done here's a half together shot showing the hub, fresh key steel and axle.