Does it say anywhere on the operator itself who manufactures the operator and or a part number that may help us identify it?

mfr = PGT, no model# visible... these are the highest impact level Miami-Dade approved 'WinGuard' units.

Upon further examination, it appears that the crank housing is a TWO-piece affair, but can't be disassembled in place, due to sill clearance. AND there's no apparent MOUNTING screws on the INdoor side either... lawdy.

Cranked it all the way open, removed screen, craned my neck out the opening, gave it a good long look and... WAY too involved to get into before the weekend, lol.

IOW, the complete opposite of "user-friendly"! To be fair, they work great, and shut out ALL wind noise from the recent Hurricane Sandy... like submarine hatches, LOL.

I've GOT to be missing an easier solution... will call an installer I know, as the PGT website is useless.

Have you tried pulling the crank directly off the shaft?

Even some older units to no use set screws, but use splines on the shaft and handle and simply press on.