I can't tell whether it was a one-off bag of beans, or me carelessly dosing too much in the centre, but things have improved. After WDT-ing, I noticed that removing the funnel/yoghurt cup the grounds were favouring the centre of the basket. I've started to jostle the grounds around in the basket by tapping the sides of the pf all the way round with my hand, seems to get a more even distribution and then just a single ~20lb tamp straight down. Looks like I probably was just overloading the middle of the basket

Good luck fixing your problems Psyd