Strainer and shower head of the coffee machine

Take the lever aside and take a look at what's going on in the head of the coffee machine. Often hidden to the barista's eyes, however, for proper water flow - and thus coffee extraction in the portafilter, everything needs to be in order in the head of the coffee machine too. In addition to the coffee head gasket, regularly check the condition of the shower strainer or the coffee machine shower itself.