Have any of you got any idea?We checked the score: it is an early (and possibly the only one) edition by Bote & G. Bock (Eigentum der Verleger Berlin & Posen), edition-number: 12398. You are right, it is not available. We found this score by our research in the Library of Congress in Washington.
Unfortunately we may not make any copy of them, because they didn't allowed us, (in Washington we had to sign and confirm it), so we can not send it to You directly. As we think, You can not travel to Washington just for "Harfagar", we would suggest to try it online. We heard, that the Library began to digitalize the scores, perhaps You can order it.
Thanks