Maintenance
Group Head Gasket Replacement: Signs and Timing
The group head gasket is a wear part on most machines, and its failure is usually obvious once you know the signs — and easy to mistake for a bigger problem if you don't.
What the gasket does
The gasket seals the portafilter against the group head, holding brew pressure during extraction so water is forced through the puck rather than escaping around its edges.
Signs it is worn
Water spraying or dripping from around the portafilter during a shot, or difficulty locking the portafilter in as firmly as before, are common signs the gasket has hardened or worn — both are direct results of the seal no longer compressing evenly.
Replacement is routine, not a machine fault
Gaskets are a documented wear item on most prosumer machines, and periodic replacement is expected maintenance — check your manual for the part number and recommended interval rather than treating it as a defect. On heavily used machines this can be closer to once a year; on lightly used home machines, considerably longer.
How to avoid mistaking this for a different problem
A leaking gasket can look similar to a loose portafilter lock or an over-full basket forcing grounds against the seal. Before ordering a replacement gasket, confirm the basket is not overfilled and that the portafilter locks in with the same resistance it always has — if it locks in noticeably looser than when the machine was new, the gasket is the more likely cause.