Hello Martin!
You can remove de right-hand crankase cover without remove generator.
Only unscrew the four in the cover. I always open the crankcase cover, it
is more clear for work. Generator window is only for setting the contact breaker gap
or sensor in electric ignition.
Remember a small steel ball into the crankcase cover clutch lifting arm, usually ball fall
and very difficult to found
I saw you wanted a gearchange shaft but I think you only need a new return spring.
Sadly for change either two pieces you need open the half crankcases.
Martin, you write in a paper colours and position of generator wires.
A old car-lift like picture help a lot; down the engine is unconfortable, it is a bit
heavy.
Haynes: the book do not talk the heat for dismantling and assembling
the engine.
Special tools: Very important, like heat, to easy work without damages.
Saludos/Regards.