Your adjustment of the needle to the twine disc looks right on.
On the end of the wiper that goes into the cam, there is a ball on the end that actually comes in contact with the cam. If that ball is there, you pretty much have all the movement you are going to have. If it is missing, this could be part of problem. Wiper would not return far enough, and would not move far enough when wiping. If that is missing, you may need to replace wiper, or replace the ball. I have never had to do this on any of the balers I have ever worked on, but it is possible this could be the problem
If this comes through. this is a link to JD parts page of the type of knotter you have. It is actually out of the 224t book, but will show the ball I am talking about on the top end of the wiper that goes into the big cam.
Error java.lang.NullPointerException
Says error, but when I just clicked it to check it, the page came right up. Try it anyway and see if it does for you also.
No mater how sloppy one of these is, I have never seen it stop a knotter from working. If the knots on that right side are still hanging up, I am still looking at how tight the wiper is. Until it takes a pull of about 10-15 pounds, they are not tight enough. The twine you have in there looks good for what you are doing. I like the length of the little shreads that are falling out of the left knotter. I do not see any for the right knotter?????
Did you remove the flat springs for the twine disc tension, to make sure that they are not stuck together? Maybe even loosen that right side up a little more. You can all ways tighten back up if needed. Also look at that right twine disc and make sure it is turning properly. Judging by the top right picture from 4-29, that is the classic look of the twine not being cut properly. If the knife is not sharp, it puts a hard pull on the twine and can really tighten it up around the bill hook.
Minor point, not the problem here I don't think, but tucker finger adjustments. They should almost touch the needle as they start moving across the face of the needle. Spacing becomes more critical as you crank more hay through the baler. This adjustment though is not causing the knots to hang on the bill hook. Two main things do that, wiper adjustment, and knife sharpness. Make sure you are 100% on these items, and the ball is on the cam end of the wiper, before you even think about doing anything else with the wiper travel.
Let me know what you find. When you hear hoof beats, think horses not zebras. Not enough wiper travel can be a real zebra answer. We need to eliminate at the horse answers first.