Not sure about the preload part. How do you do that? Packed bearings with grease. Used FSM procedure as stated. New bearings and races. Used the slotted washer. Races properly seated. Castle nut and cotter pin in place.
If you followed the FSM to the letter, they should be "set." There's only so much in there that can go wrong. what you have described (taking up 1 more turn) is extremely troubling