Zeiss-Opton Tessar - not what I expected!

Thanks Sandeha! I have a groundglass so that seems to be the first thing to do. I'll start from there.

The top lens of the Ikoflex (at least the one I worked on) is a double-nut. You adjust the lens simply by screwing it in and out. Then the lock nut (around the front) simply tightens and holds the lens in place. I guess it works but it seems likely to wiggle out of alignment if you ask me. Set the camera at infinity and make sure the top focus screen is in focus.
Then check that the bottom lens is in focus.

I do not think that the main problem is a focus offset between viewing and taking lens. Look at picture #2: center is (more-or-less) sharp, periphery is soft; focus offset would produce uniformly soft image of this flat and distant building.
I vote for one element having been flipped front-back. I saw this on a Fujica GS645W bought at a photo exchange, IQ was terrible; after proper re-assembly it is now delivering superb IQ.
I suggest dis-assembling the taking lens, carefully recording the orientation of elements as found. Compare with Tessar diagram. The viewing lens canot be taken as a secure reference: whoever messed up the taking lens might have put his hands on the viewing lesn also...

On reflection, Bernard may well be right - in which case you should see it quite clearly with the ground glass on the taking lens.

I also vote for the tinkered with lens theory.