Wrote you in the e-mail and then opened this thread. So, If you, Michael, install the original LNB holder, then the middle of the Ku-band LNB will be approximately where I painted the red dot. And this red dot represents (approximately) the position of the focal point of the dish. LNB's phase center is located approximately where the green circle is painted. Your task would be to make sure the red and the green are co-located. Therefore , the LNB should be moved much lower, when the feedhorn almost touching the feedarm. If needed, the threaded pin (pointed by the orange arrow) can be removed, and the metal plank (pink arrow) can be slightly bent.
And, if you got some channels from 20*e, congratulations on that, but that does not mean the LNB is placed correctly. But you have time!