If you want to tune it for best sharpness, you have to be scientific about it.
It has to be tripod mounted, SR off, use self timer, and wide open (f/3.5 and f/4.5 are pretty forgiving, have lots of DOF, but that's the character of that lens).
You need to look at the image at full raw resolution, zoomed in on the PC. The 3 JPGs you post are from different positions (you moved the camera), and the JPG compression gets rid of the sharpness of the text and the edges, so the target doesnt have enough detail or sharp edges to tell. So work with Raw (DNG/PEF). To cut down posting size, crop just the centre of the image, but at full resolution.
I've had good success with my K-1 and 645z with the Michael Tapes Design LensAlign tool and software. Works very well.
It takes at least 30 minutes to nail it.
Previously I used the Spyder LensCal, and I get better results with the MTD product.
LensAlign - WhiBal
and you can get it from B&H and others.
The other thing I've found is that a variation of +/- 2 is enough to make a big difference, so you need to find where it looks sharp, and shoot about 4-5 shots at each setting, and then go up and down a couple of settings, otherwise you may blow right past the in-focus sharpest point.
Another trick is get some AA batteries and line them up with each one a bit further behind the other, off on a diagonal, all with the label text visible to the camera. It makes it easier to tell when in focus precisely.
Good luck and have fun.