I believe I never got an older revision than s5 or s6. To try them individually, you can plug the bottom one to the dual breakout hoard. This way, even voltage adjust works with a single PSU.
The pinout for the PSU have to be the same on all revisions, or you'll have trouble on the servers. If the breakout board works with one revision, it'll work on all unless the very old revisions are using another pin combined with the one I use to turn on the PSU.
Or you may have 1 or 2 dead PSUs.
Thanks J4bberwock. Neither PSU turned on for me. I'll try them individually next chance I get which probably won't be until Monday or so.