Thank you all for your help - now it is very clear for me!
So I have first to truncate the respective table within the database and then I have to go to import the current data with SEBLOD Importer.
That's what I did now. And it works.
But there is another unexpected reaction! The list view with those records shows on the first 7 pages the correct data within the correct sort order. But after that there are additonal 7 pages with no content in the search list! And the database is really reduced to the current 152 records.
Would you review it? It's on this site - and please pay attention to the page 7.
It would be very appreciated if you have additional hints what's to do!
Best regards
Heinz