(especially to Frank) : Yesterday was my lucky day. After the conferences, I felt too tired to visit the city and just had a quiet lunch in the near-empty orangerie. Then back to St Michael church, 100 m away. Had a chat with the "Küster" (sacristan) about the origins of the building and the al fresco paintings.
Then about the organ, which was "open". The sacristan said yes, the organist had left the shutters open. Of course there would be another mass later on, he said, but leaving the shutters open was no good idea, "da könnte ja jeder kommen" (typical German expression for disapproving exceptions to rules, because then "everybody could come up" and enjoy said exception). I said, yes, indeed, me for instance. He looked astonished; I went on saying that I was an organist. Then he said "maybe you do not know how to get it started". I replied "well, I guess you have to pull the Fischer+Krämer marked stop". That last response convinced him that I knew how to handle this contraption; Fischer+Krämer is the name of the organ building firm, and instead of having a standard electric switch for the blower, they disguise it as a stopknob, see photo.
So I sat at the organ for half an hour, getting my "sheet music" from my Surface PC. The sacristan went back and sat at the entrance to sell his postcards. Having finished playing, I warmly thanked him and wanted to leave a banknote for the maintenance of the organ, or maybe for him. He said fine, just put it into the box for collecting offerings. Bravo, Sir. There are still sacristans with some apparent integrity on earth.