yeah sounds like a little corrosion on the stator... might just be a little damp if its not rusting id say a little gasket seal on the rubber plugs and seal will fix it
only way i'v seen people clean it up is sand it off lightly with some sandpaper, but it can be a pain in all the nooks in a case like that. and you gotta be carefull not to get any filings in the seal too