A happy end.
I brought the 1911 Champion to my local gun smith, but he could not resolve the problem. He sent the gun back to the factory for repair.
Last week it came back and I took the 1911 Champion last Saturday to the range. I shot 150 rounds, (50 Remington and 100 Wolf steel cased rounds).
The gun worked flawless without ANY problem at all. Just like my regular 1911A1 Springfield from 1989.

(I used up my last Wolf leftovers, but I'll not buy them again).
I do not know what exactly they have fixed in the factory, but I noticed a new extractor installed by the factory's gun smith. I guess, the extractor could not cause the problem, because I exchanged the original extractor for another original factory replacement extractor and I had still the same problems.
(I kept the replacement extractor and brought the gun with the original extractor to the gun smith. The gun was sent with the original extractor to the factory)