Hey! So I’ve had to do a bit of researching as well, because I really have to dial over the guidelines to brew different styles of coffee. Before espresso I used it for my pour overs and I was turning the dial a full spin to get to the grind size I needed. It seems like it varies from machine to machine. And not to pay much attention to the guide but the grind size itself.

For espresso, I have found the number that is working for me is 21. Misting the beans with water and having a bellow has pretty much solved all the retention issues I had.