Problem solved - your hint was extremely helpful. Really, the Engine part was corrupt. My previous post of Engine was an excerpt from my BACKUP copy of weewx.conf (taken before uninstall). Due to my uninstall the entry archive_services was completely corrupt into
archive_services = w, e, e, w, x, ., e, n, g, i, n, e, ., S, t, d, A, r, c, h, i, v, e
Now weewx 4.7.0 is up an running. Of course I did a comparision of "my" weewx.conf with the new one from 4.7.0, but based on my BACKUP copy.
Thank you very much, Michael