After a few months of being busy with other things, the machine is now running (not on E10 fuel). After getting the engine going, I could not get power to the blades/rear roller.. It seems that the clutch was stuck in the disengaged position. I pulled the engine off to get the clutch off to have a look for the problem (was pleased to see no cracks in the base plate) and in doing so the clutch cone became unstuck (I had not realised that it had to move - I had assumed all movement was internal). That was the end of the problem. I took the clutch off and pulled it apart anyway and like everything else on this machine, everything was in a good way.
I think I will cut grass with it this summer and then do the full resto over winter 2021.