Those 3D printed dishwasher rack protectors solved the problem on the bottom of the pins, but the tops also had some rust. I dosed the pins with Evapo-Rust to stabilize the corrosion:

After that picture, the pins soaked for a while, got a rinse & blotting, then sat for a while to dry. I can’t say that’s in complete accordance with the directions, but it’s close to the spirit of the thing.
Meanwhile, the MEK / xylene / acetone I added to the bottle of stiffened ReRACK repair coating had softened it up pretty well. They recommend several coats at half-hour intervals, of which this was the first:

I probably should have chewed off the corrosion bulging the OEM coating, but, given the number of pins that needed chewing, that started looking like a major project. Let’s face it, I can always touch things up if the pins continue rotting out.
The next morning, the rack was back in service:

One advantage of a big blob atop each pin: the printed rack protectors might not wriggle off quite so easily.