Masthead Sheaves--re-cut old aluminum or buy new delrin?

[JohnV]

Douglas,
It looks like a press fit, with no insulating layer that I can see. I'd surmise that the fit is tight enough to exclude water, and I don't see any corrosion. Just a little soft black surface crud, which is probably dry lubricant.
I believe them to be original to the Lefiel mast, and their reputation, from what I gather, seems pretty good.
Plus, they're 30 years old and have lasted this long, so while it's sensible to think corrosion would be a problem, it obviously hasn't been.
John