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As you probably know, AK was a german manufacturer so maybe you can find some more info on a german board. Here's 44 pages of Kotter knowledge, maybe post a picture there... the forum is generally helpful and friendly.
http://www.rennrad-news.de/forum/threads/albuch-kotter-kult.40365/page-44
My Olmo is in the current projects section, here's the link: https://www.lfgss.com/conversations/285264/?offset=25
With the fork included it weighs 2,8kg