Removing Spring Plungers from Trackspots

I've never actually had to replace them, but of course, now I do and can't seem to figure out how to get them out of the fixture (or back in) without destroying them. Whats the magic method or tool for it?

To adjust i've always just used a vice grip to tighten or loosen, but that seems to destroy the threads at the top of the bottom of the screw.
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