In the shop I work for the past 8 months, we use KR804 for single origin and decaf shots.
Here’s the details of our recipe for store use
dose 19.5g +/- 0.5g without RDT aiming 39g-42g output to start
usually range 27-33 seconds will begin to get some drinkable shots
and then however the results are, we would adjust towards the direction we desire.
still too early to say I know KR804 well; there are a lot more people know this machine better
Furthermore, there are some youtube videos for cleaning and realigning KR804 to get more accurate adjustment
I would probably look at those parts if you’ve tried adjusting every possible way of grind setting
I don’t know if misalignment ever is an issue with KR804, but why not tried to take a good look at your burr first?
Just some thoughts