[DangerMan]

I've heard it said that a dishwasher is good for such deposits but haven't tried it myself... I've never really fancied a rolling pin right between the eyes!

Before we had such a device I did have to restore a tuning gang for a very poorly SAD94, and removed the rotor assembly so I could use various grades of wet and dry finishing paper (as used for car body/paint repairs) to sand away the crud between individual vanes, finishing with very fine grit (800 or 1000 grade).
The backing material is sufficiently strong to allow you to get a good push and pull sanding effect although it takes a while and many narrow strips (doubled over so sanding on both sides if need be) depending on the amount of corrosion.
It's also water proof, so can be best used wet, acting as a lubricant and to continuously clear away the removed crud.
Once cleaned of the large blisters back to the aluminium the thin film of oxide that immediately forms on the metal is sufficient to prevent further corrosion in the absence of damp.

Mine looked far worse than yours but after a good clean up and reassembly with greased bearings, after nearly 20 years it is still going well... in dry conditions.

It might be possible to use the same technique without removing the rotor, but I'd be worried about grit from the oxide or the wet and dry paper getting in the bearings.

Pete