This morning I tried the advice given in How To Avoid Making Sour Espresso. To simplify the process, I made 2 double shots and upped the amount of non-dairy milk to 3/4 cup. The first double shot was made with 2 scant scoops of beans ground a 1/2 step finer. This was too fine. The espresso machine initially clogged, than pumped out espresso intermittently. The resulting double shot wasn’t sour. The second double shot was 2 scant scoops of beans ground at my usual setting for espresso. I timed the double shot at 40 seconds. The article recommends 20-30 seconds. I am unclear if this is for 1 shot or two. It tasted bitter, thin, and over-extracted. The two double shots combined in the larger amount of milk was decent. Better, but not what I expected from such a highly touted coffee.
About all I can think of at this point is measuring the espresso cups to find where 1oz/30ml and 2oz/60ml come to and clarify the pull timing.