A twice weekly cleaning of the group heads and showers should be performed on a regular basis. The shower screen and diffuser are located up in the group head and are held in place by a screw. After removing them just soak them in water overnight with a small amount of machine detergent. Rinse well before replacing.
The rubber gasket located in the group head will also need to be brushed clean. This gasket may become worn over a period of time, and will need to be replaced.
A good indication that this gasket needs replacement is when the grouphandle (portafilter) returns beyond its normal right angle position, or water starts leaking out around the group head during the brewing process. Our tip: During slow times and at night, put your grouphandles loosely back in the machine (do not lock them in tightly). This will ensure your group gaskets stay longer.