I have vinyl coated lifelines on my 1983 C&C 35 that are showing some rust staining at the swage fittings. What's the proper way to inspect them?

When I do replace the lifelines, is it better to use uncoated 3/16"(Defender lists 7x7 strand for lifelines) rather than the vinyl coated because of the potential corrosion problems?

Thanks for any advice