I was setting my sag yesterday. Started out with 8 clicks on the rear shock and got up to 20 easily.  I was not making any adjustment in the sag after 12 and went to turn it back down and it won’t turn.  Obviously I need a stiffer spring.  How bad did I screw up?   Looking at the movement in the shock (dirt line) I adjusted down about 5-7mm. 

Didn't screw up, the book says up to 24 clicks. You probably got some poop in the adjuster threads. Clean it up when you mount the new spring.

When i was playing with my preload adjuster, at certain point got stuck.

 

I guess something heats up and the knob stop turning.( i could feel it warm)

 

Let it cool down and will be fine

I thought I had the same problem once - couldn't hear or feel any clicks (mid-adjustment range, 85nm spring). Then, next time I tried it was fine. Not exactly a solution, but maybe the "problem" is intermittent.