Nice machine work! My Gen 4 19 is flawless, but I feel for those who have problems. The answer to the problem has been so allusive I'm guessing that there is more than one problem. Seems like those who have the know how to make several changes get the best results.
"A little learning is a dang'rous thing; Drink deep, or taste not the Pierian spring: There shallow draughts intoxicate the brain, And drinking largely sobers us again."