I know your problems already been solved but i had issues with charging due to a dented dynamo cover which in turn had the field coil tweaked inside causing contact to the rotor. did every single electrical test known to man for these bikes and came up with a defective field coil a couple times and a couple other times it tested good.. measured the difference in depths with a straight edge across the gasket surface and shimmed it straight, adjusted the regulator gap and taa-daa good as new-ish ; )
Long story short if your dynamos scratched/dented check the gizzards.
Josh