I have to admit I have never used a plow on a PK tractor I'm hoping to try it this spring when the ground dries out. It is all mounted and ready. I have plowed a few thousand acres with a 7 bottom JD on a JD4850. In your picture of the tractor plowing it looks like you are trying to plow to deep . At the most you probably have a twelve inch plow, which is meant to plow no more than 7 inches deep. If you are trying to plow sod ground, the coulter is a must.
The first thing you have to do is get the plow hooked to the tractor in the right place on the drawbar which is dependent on your rear wheel spacing. I can't tell you what that is at 10:45 at night because my book is in the garage. After that is set, you have to try it and see if you plow is biting off the 10 or 12" it is supposed to. If not , there is an adjusting screw on the bottom of the plow beam which changes the angle of attack of the plow. Tighten it and it takes a bigger bite loosen it and it takes less. To change it you have to first loosen the bolts that hold the moldboard to
the beam. Before that , first thing put the wheels on the left side of the tractor up on 7" blocks to simulate the tractor position when the plow is in the ground. The beam of the plow should be at a 90 degree angle to the ground. After that try it again then if it bobs up and down you have to shorten the top link which hooks the plow to the tractor to point the plow down in the ground just enough to a little tension on the lift arms.
On a full size tractor, the top link is fastened to the bottom hole on the tractor and the chains are never tight, the plow must be able to swing right or left. Start with the wheels up on blocks for the first adjustment. Hope this helps.