Oh well, turns out that the only thing worth something was the nib (14k M with that star emblem and size mark). Or so it seems, currently.
So I managed to salvage it and the feed. Collar was busted, split in two with the threaded part stuck in the section. I cleaned both and mated them to a spare collar I had available, niiiiiiice... it looks super, but unfortunately rather firm (semi-flex at max). The tipping is worn a bit flat but there is still healthy amount of it. Imprints are very good, crisp and clean.
But oh boy, was that thing gunked! I think it was left with IG ink in it, had really hard time to get it to soak off and had to spend a major amount of time brushing and scraping the feed and the ink channels clean. And the nib took some effort too, stuck ink all over and fair amount of tarnish.
The barrel, which is actually celluloid, might be ok although I doubt it. There is a fair chance that the section (which had some tool marks) leaks. Or then you have the usual enough to almost expect them as a norm micro cracks on the cap threads. Time will tell...
Binde was busted too, ink window end of it was worn so thin it flaked off the pen and the rest soon followed.
Filling mechanism is firmly stuck into the barrel, will try soaking the damn thing overnight. Piston knob had tool marks... might be able to sort those out. Have a spare mechanism available though but that one needs a new cork.
Cap... well, it was so well worn on both ends that I can only conclude that this pen has seen quite some miles in it's time... Clip is so so, into the parts bin it went.
So all in all, it is not a complete lemon but way worse what could be observed from the photos. If all goes well I have parts for a Pelikan 100 "Frankenpen" edition. At the minimum it needs a new piston seal... and a new binde, might go crazy with that. Like order a chased jewelers binde out of sterling. Oh, the hard rubber parts need some loving too.
Ok, so far I have bought two celluloid barrel 100 for about 60€ total knowing they have issues. The other one came with a busted "14k Warranted" replacement nib. If I can manage to salvage the barrel and get the stuck bits sorted out I can get a working pen after the piston seal has been fixed. So not entirely horribly bad still. And that nib looks pretty darn sweet, I would be happy just for that even if all the other parts turned out to be junk.
Have I learned anything from this? There were those few points during this evening where I almost found myself swearing off of these particular old birds but... what can I say, I am a hopeless romantic with a tendency towards optimism when it comes to vintage pens so I will keep on searching "that right one". Pelikan 100 are really sweet and neat little pens if they are in great shape. Sadly, that is often not the case with the ones found in the wild but I suppose the challenges presented are one of those things that makes it all interesting...