Learn how to replace the group gasket and shower screen of an ECM Elektronika II Profi espresso machine.
For the average home user, the group gasket should be replaced about every six months to a year. When the group gasket is worn out, it becomes hard, and no longer creates a good seal between the portafilter and the group head, so you may begin to notice some leaking. When a group gasket is really old, it can be extremely difficult to remove from the machine, so even if you don't experience any leaking, replacing the group gasket on a yearly basis is a good idea.
The document attached at the end of this article shows how to replace the group gasket and shower screen. You don't have to replace the screen once a year, as typically it can simply be cleaned.