Go pick up the strongest wheel cleaner you can find at the local autoparts store. It should have some light acid in it. When I have to detail big rigs or aluminum pontoons on boats, I have to strip them first with acid to buff them shiny.
When I'm rebuilding them for resale, I normally just replace the rollers and paint the housing. I've tried several different methods on the rollers and they all end up looking like crap after a few months.
“The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed.” ― Robert M. Pirsig, Zen And The Art Of Motorcycle Maintenance: An Inquiry Into Values
All those steel rollers are zinc plated with a clear chromate on them. Once they have started to corrode you only option is to have them replated or just clean and paint it. And scrubbing with sand paper or steel wool will just remove the zinc then they will just rust.
I bet WD40, some steel wool, and some elbow grease would go a long way. Works well to clean off any oxidation or rust from metal surfaces.
Didnt think about WD40. Far as that goes rubbing compound might work. Thought what I was looking at was oxidation. I guess it could be corrosion? Dont think I would target the actual rollers with paint. Seems like paint chips would eventually fill your drum and decorate your line.
The black spots you see is the zinc plating all ready corroding where the chromate has worn off. Paint or not its not a big deal and yes your wire will remove the paint. If its that big of a deal swap to a synthetic line and buy an aluminum fairlead. A new roller is about 30.00 bucks out here.