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Separate a grinder that does not start from one that hums against a blockage, or turns without delivering grounds. Stop repeated attempts when it stalls. A change in sound after cleaning or hopper removal is useful evidence; it is not permission to bypass an interlock.

Model and procedure boundaryBES878 Barista Pro. Burr assemblies can vary across production revisions. Use the instruction book supplied with the machine for owner-removable components, especially before applying a video made for another Breville grinder.

Which observation matches?

Choose the closest observation. The complete decision list remains below.

The grinder is completely silent

Confirm the hopper is correctly seated and locked and the normal controls are being used. Do not hold down a safety switch manually.

The grinder hums or stalls

Stop pressing the grind control. Turn off, unplug and allow it to cool before a permitted inspection.

The mechanism turns but grounds do not emerge

Inspect the hopper feed and accessible chute using the owner-cleaning procedure.

It became stuck after burr cleaning

Check reassembly against the exact manual. Do not force a burr or change internal alignment by trial and error.

Safe checks, in order

  1. Write down whether the fault started with new beans, a grind adjustment, a spill or recent cleaning.
  2. Turn the machine off and unplug it. Follow the manual to remove beans and owner-removable parts; keep fingers and metal tools out of the mechanism.
  3. Use dry cleaning methods and the supplied brush where prescribed. Do not pour water, rice, oil or improvised cleaners into the grinder.
  4. Reassemble exactly as specified. If the supported cleaning has not resolved the issue, arrange service rather than repeated stall tests.
Representative semi-automatic espresso machine; not a photograph of the exact BES model.
Representative semi-automatic espresso machine; not a photograph of the exact BES model. See the manufacturer reference for exact components. Photo credit and license.

A silent grinder is not the same as a blocked grinder

The first case may involve a control or assembly condition; the second has a different sound and risk. Sending a service agent that distinction can save unnecessary parts speculation. Record a sound only during normal safe use, not by intentionally stalling it again.

Before buying a burr or motor

Match the complete machine code and assembly revision, and obtain a diagnosis. A hopper interlock, obstruction and motor fault cannot be reliably distinguished by the phrase "not working" alone. A universal part listing is not proof of compatibility.

Stop and obtain help when

Stop for a burning smell, a foreign object you cannot remove with the supported owner procedure, persistent stalling, damage to the burr assembly or liquid in the grinder. Do not open the motor housing.

Questions this diagnosis does not skip

Should I keep pressing the grind switch until it clears?

No. Repeated stall attempts are not a supported clearing technique.

Can I follow a Barista Express lower-burr teardown?

Not as a substitute for the BES878 instructions. This guide limits work to owner maintenance, not internal repair.

References and evidence

Manufacturer facts and procedures are referenced above; the observation comparisons are our diagnostic synthesis, not proof of a failed component. Photos are illustrative, not evidence of hands-on testing. Editorial standards | Report a correction.