Well.....I managed to get out the firing pin and retainer plate, then removed the bolt stop and recoil spring. But still, the bolt was reluctant to leave.
I tried the takedown latch again, and jiggled the slide while I tugged on the bolt.
VOILA! The bolt stopped at the hammer, so pulling back slightly on the hammer, I eased out the bolt. I took off the bits around the lock, and now I'm left with two dilemmas.....How to get the trigger subframe assembly out (it's not like the later pistols), but most importantly, I'm presently stumped as to how to remove the rocker coupling, as it sits in [I]front[I] of the mainspring and plunger!
Geez....every part is correctly serial numbered 5866.... except for the takedown latch (27) and the disconnector(just a crown). Lots of letters (and crowns) here and there, too.
While I'm pondering the rocker coupling and mainspring, what is a good solvent for removing dried grease. There's no rust, thankfully, and I'm fascinated that the rocker coupling is a very shiny yellow steel - must be from that Krupp guy

As for lubricant....Rust Check, or G96? Something a little heavier?
Thanks again gents, especially Postie.
Cheers,
Bill