Keep in mind that flair 58 and others machines (decent espresso) needs a finer grind than a normal e61 machine/linea etc. Same for a Pavoni with ims basket it needs finer grind than the above. I am not talking about extended preinfusion= finer grind, i’m talking about using the same basket in e61/linea vs decent/flair 58 the same dose and preinfusion for some reason the later needs finer grind.
To align the grinder better would give you more leverage to play with grind size. Other things that you can do is:
-use frozen beans- generate more fines= grind coarser-
-use certain paper filters at the bottom- some speed up some slow down the flow in the cup-
-use a higher dose if the basket permits-
-change the basket- from a high flow to a normal one, from a VST to a normal 58mm basket, or even to a conical shaped.