Thanks Randy and TenGrain! I'll touch it up.
When I build the Roo, I might go for full paint, worried that more of those oxidation snakes might start showing up. That might be, perhaps, over kill but I have no love for purple so, though I rarely recommend full paint, the damage to the Roo is sufficient to more than warrant it, in my opinion.
For the OP, touching up will mean cleaning the contaminated area and well beyond. Leaving any oxidation will result in more deterioration.