Success!
The overnight stay with "loaded" hydraulic lifter "oil bled" all of them. They all showed the same soft spring effect. After that it was easy to adjust the lifters. I noticed, when you look now from the side, that all adjustment nuts are on one line. Before there was a significant variation. Before the adjustment the compression tester showed variation of 3 bars between the cylinders which are now down to less than 1 bar indicating that some of the valves were not properly closing. Thank god that I did not burn any of the valves.....
Brgds
SIG