There was two major issues and one minor one which I have resolved.
First, a small section of maybe 8 teeth on the mainspring barrel was damaged. The only proper way for repair that would be to manufacture the whole barrel but there are two disadvantages to that. i) The character of the watch would be permanently marred. ii) And the cost. So I filled the damage with silver (harder than lead so will last longer) by welding silver solder. And this is now allowing the winding pinion to grip the barrel throughout the 360ºs.
Second, excess wear on the train wheel bridge (originally thought it was the main plate) which was causing too much movement with the winding stem. With this I had no option but to weld some packing material (sterling silver) to the bridge and then re-shape it back. This was successful.
The minor issue was the setting lever screw, which was missing and allowing the winder to be pulled out of the watch. I re-worked a screw from another watch of similar age and this is now doing the job of retaining the winder just nicely.
Finally, I cleaned and lubricated the movement.