error: multilinguality/utf-8 vs ISO?

Hi, for some reason, one of my posts doesn’t display Umlauts properly:
https://www.iroke.de/wp/2005/05/22/the-first-200-days/
There are other posts on the site (i.e. under “Japan”) which use Japanese character with no problem, but not that post. What’s wrong with it? I tried to save it with different configurations per Textcontrol, but that didn’t help.
Any thoughts are highly appreciated…

p.s.: I took a look into the database: what’s the difference in the database between post_content and post_content_filtered? what’s filtering it, the text filters I enable for each post (i.e. texturize1 or wpautop?)

I had a scrambled character in it, too, but when I put it back to ?¤ the post still didn’t look right. In the post_content_filtered cell the “Schr??der” read “Schröder” (with & Atilde ; & para ; ) which is not right as well…

There’s no difference whether I choose wptexturizer, smarty pants or no encoding… :-/