HI Rob,
thx for your message. After having read the respective paragraph in the manual I decided to try it again. I removed the cover of the regulator and started the engine. At low idle revving of the engine there was no "action" visible of the regulator. But if the engine revs higher suddenly one of the switches of the coils closed a circuit and the amperemeter indicated charging.
So I expect that the charging system will work under running conditions as it did the years before.
Unfortunately when I was taught physics at school I wasn`t aware of the relevance of this subject for my later life ;-)