Charging headaches!

[Joolstacho]

Latest: I've changed the Rotor and the Stator with (good used) '07 model units. (my bike is an '89). The nasty clattering noise at lowish rpm has gone, - it was a stuffed starter clutch, so now I'll avoid embarrassment at the lights!
However... to get to the lights I need a bike that charges it's battery, and I still have the charging problem. Still getting only 12.3-12.4v at the battery terminals, -no change with revs or lights.

BTW in swapping the stator I noticed that the '07 stator is different to the '89 one, it is same diameter, but thinner by about 4mm, so it mounts a little lower in the cover (so it would be a little further out in relation to the rotor). Has anyone else done this? It changes the alignment of the rotor and stator slightly, I wonder if it'll affect output.

So anyway, still looking for ideas on the charging problem.