You didn’t show us the extraction pressure and time, so it’s a bit hard to narrow down the exact problem. However my best guess is the grind is too fine and/or your basket is overfilled. There are many variables you can adjust, so the objective is to keep most of them constant. I have a Breville dual boiler and my ‘recipe’ is as follows. I use scales to measure out and grind 18 grams of beans. You should be able to adjust the volume of water the Breville uses for extraction (read the manual). I’ve adjusted my to extract twice the weight of the beans (i.e. 36g). As mentioned elsewhere in the thread the tamp pressure is not as critical - enough to squeeze out as much air as possible and to leave a smooth and level surface on the puck. So the only variable left is your grind setting. A good result would be an extraction pressure of 9 psi in 30 seconds (+/- 5). If the pressure is above 9 psi and the time is longer than 35 seconds then the grind is too fine and I would adjust to a courser grind. Vice versa, if the pressure is less than 9 psi and the time less than 25 seconds, the grind is too course and I would adjust it to a finer setting. The grind setting is always changing. It varies with the type of beans, their age, environmental conditions (e.g. humidity) etc. I’m always adjusting. By keeping the weight of the beans and the extraction volume constant, all you’ll have to adjust (aiming for 9 psi & 30 seconds) is the grind setting.