god damn nearly runined my primary disk with the Windows installation. I already knew that creating an image with Windows didn't work. And due to the cloning failures I had before I was stopping the windows snapshot feature and a few other things.
I used unetbootin to create a EFI bootable Clonezilla on my USB stick. I booted into Clonezilla and started the cloning. When I was finished I shut down the PC and swapped old SDD with new SSD. After the startup Windows tried to repair and failed and failed and failed and failed. So I went back to my old SSD. Strangly (not really at the end) Windows also tried to repair that SSD. At the end I got Device not found bla bla bla with error code 0xc000000e.
Nice ...
After a lot of testing I realized that booting into the stick again I could do the fixmbr and a lot of other commands for the rebuildbcd and so on. Finally I got my old SSD working again.
I know what caused the problem. I let Clonezilla do a fsck with the option to repair manually. This was a mistake. On my 2nd turn I just skipped fsck. That helped.
Same for the new SSD. Somehow the copy didn't work in the 1st round, maybe the fsck of the source caused this too. At the end I saw that the volume with the Windows installation was unusable because it was displayed as RAW, which means with errors.
On the 2nd cloning round everything was perfect. The PC immediately came up with the new SSD. The old SSD wasn't damaged either.
What now remains is that my recovery partitition needs to be moved to the end of the SSD because it blocks extending my Primary Volume for the OS.
Maybe I have todo it with Gparted. ... let's see.
And I thought I could use the dd command muahahah. This would have probably never worked with my little Linux knowledge ...
Well the PC is faster with the 850 Evo M.2 than with the old SSD, but not what I originally wanted when buying the 950 Pro M.2. Damn.