some of my full stamp panes

If the paper surface there is undamaged, then it is usually caused by some obstruction (e.g., paper scrap...) that clung to the plate and didn't get wiped off on the previous print, or some adhesion to the paper itself just before the print. If you hit it with filtered long wavelength UV light and it glows just like the rest of the white paper, then that's what it is. If it glows differently, then there is some paper surface damage. But your perf holes appear undamaged, so I'm voting for adhesion/obstruction during printing. That would make it a printing freak.

Great scans, Jeff! Great reason to stay up late!

Remember, no pane no gain...

There are a LOT of EFOs not listed in Brookman. Typically, catalogs will only list only as far as constant plate varieties. I don't think your EFO is a constant plate variety, but it's worth a look in the catalog.

Did you know that besides collector value that these stamps have no value or purpose? ...at least anymore that is. When the USPS discontinued special delivery it made these obsolete and they cannot even be used for postage. So, if you bought these and didn't read the paper that day you was pretty much out of luck! However IO have used these as postage in recent times (but not from this pane) and they were accepted but probably by an ignorant or young postal worker.  I thought I'd share my thought with you.