Machine makes loud knocking, grinding, or squealing noises during brewing.

Safety first: Unplug the machine before inspecting internal mechanisms. Keep fingers away from moving parts.

Step-by-step:

• 1. Isolate the source: Listen carefully to determine whether the noise occurs during grinding, brewing (brew unit movement), or pumping.
• 2. Service brew unit: Remove the brew unit, clean it, and apply a thin layer of food-grade silicone grease to the sliding rails and piston as recommended by Siemens.
• 3. Check for loose parts: With the cover removed, inspect for loose screws, panels, or components that may vibrate against the housing.
• 4. Inspect grinder: Empty the bean hopper and check for stones or hard objects. Vacuum out loose grounds.
• 5. Professional repair: Persistent loud knocking or grinding may indicate worn gears or a failing motor, which should be replaced by Siemens service.