The shower screen is held in place by the gasket and is designed to be easily removable for regular cleaning, which also means it can be dislodged.
Why it may come loose
If the portafilter is removed while there is still pressure from a purge, that pressure can push the screen out with it. Coffee residue in the seating groove, oils or water can also weaken its grip over time.
Reseating the shower screen
Remove the screen and wipe the seating groove with a damp microfiber cloth — the goal is zero coffee residue or debris where it seats.
Wash the blue O-ring with water and a little soap to remove coffee oils.
Make sure the gasket area is dry as water droplets reduce its grip.
Reseat the screen, then lock in the portafilter to press it fully into place.
If available, apply a thin film of Molykote 111 around the O-ring before reinstalling. (It's the same food-safe grease we recommend for piston O-ring maintenance, so it's worth having anyway.)
Removing the shower screen for cleaning
The first removal can be difficult! Two things change that completely: grip it with a rubber kitchen glove and use a small spoon as a gentle lever.
If it keeps falling out
Do the full clean-and-reseat above once. If the screen comes loose again after that, write to us. It is possible that it is out of tolerance. Include your serial number and photos of the shower screen from multiple angles.