On another note, and this may just be part of the learning process, when I used the single portafilter with 18g of ground coffee, the water struggles to get a good flow through - would this be due to the grind of the coffee and it being compacted too much therefore making it hard for the water to get through?
Never really had this issue with the double portafilter.
I also note the single doesn’t quite lock in to 90 degrees but is very tight