No water from group head when brew button is pressed; pump may run but no flow at the portafilter.

Safety first: Turn OFF and unplug the machine. Allow the group to cool before disassembly.

Steps to restore flow:

• Check without portafilter: Remove the portafilter and run a brew cycle. If water flows freely, the basket or coffee puck is the issue (too fine grind or over-tamping).
• Clean group screen: Remove the screw holding the dispersion screen and jet plate. Soak these parts in espresso cleaner, scrub, and rinse thoroughly. Reinstall.
• Backflush with detergent: Insert a blind basket and run several backflush cycles with espresso machine detergent to clean the 3-way solenoid and internal passages.
• If still blocked: The group solenoid may be clogged with scale. Remove and clean or replace the solenoid valve using OEM La Marzocco parts.
• Severe scale: If flow remains poor, the internal brew circuit may be scaled and require professional descaling.