The grinder is the heart of espresso. If it stops working, the whole café grinds to a halt, and neither the best machine nor the freshest beans will save you. Grinder problems usually come down to a handful of recurring causes, and you can often diagnose them yourself before calling a technician.
The grinder jams
Symptoms: you press the button, the motor hums, but the burrs don’t turn.
Most common causes:
- Worn burrs that no longer “grip” the beans.
- A faulty start capacitor, so the motor doesn’t start at full power.
- Coffee path blocked by clumped fines or a foreign object, a small stone, for example.
Fix: - Check the burrs visually. If the edges look worn smooth, replace them.
- If the grinder starts turning when you nudge the burrs by hand (with the power disconnected!), the capacitor probably needs replacing.
- Take the top apart and clear out debris with a brush or compressed air.
No coffee comes out of the grinder
Symptoms: the grinder runs, you can hear the motor working, but no coffee appears at the outlet.
Most common causes:
- A loose screw holding the outlet chute, so coffee spills inside the housing.
- The grind set too fine, so fine particles clump together and block the outlet.
Fix: - Tighten the fittings at the outlet.
- Set the grind 1-2 steps coarser and clean out the outlet chute.
The grinder overheats
Symptoms: after a few minutes of use, the housing is hot, and the grinder slows down or switches itself off.
Most common causes:
- Too much fines and coffee residue inside the housing, blocking airflow and cooling to the motor.
- Long, continuous grinding, especially with large orders in one go.
Fix: - Clean the inside of the grinder regularly, clearing out fines and coffee residue.
- During busy periods, take short breaks between grinds, or run two grinders in rotation.
Espresso shot times keep changing
Symptoms: one shot takes 20 seconds, the next takes 35, despite identical settings.
Most common causes:
- Worn burrs grinding unevenly, some particles too coarse, some too fine.
- Old residue building up in the outlet chute and mixing with freshly ground coffee.
Fix: - Replace the burrs. You’ll see the difference in consistency straight away.
- Thoroughly clean the whole path, from the burrs to the outlet.
The grinder doesn’t switch on at all
Symptoms: nothing happens when you press the button, no sound, no movement.
Most common causes:
- A disconnected power cable or a faulty socket.
- A safety switch that isn’t engaged, for example after removing a cover.
- A blown fuse inside the unit.
Fix: - Test the cable and socket with another appliance.
- Make sure all covers and parts are properly fitted.
- If the fuse is blown, replace it with an identical one.
You press the paddle with the portafilter, but the grinder doesn’t start
Case 1: the timer on the display counts down, but no coffee comes out
- The grinder is likely clogged with ground coffee: the outlet chute has been blocked by clumped fines or a foreign object.
- Fix: switch off the unit, take the outlet apart and clear the blockage, then set the grind a touch coarser to reduce the risk of it clogging again.
Case 2: the timer doesn’t run at all
- Most often the micro-switch triggered by the portafilter’s paddle has failed.
- Fix: replace the micro-switch, ideally with the exact model the manufacturer recommends.
A coffee grinder is essential kit in a café, and it’s worth looking after
A coffee grinder is one of the most important tools in a café: when it fails, it can bring the whole place to a standstill. Most problems come down to worn burrs, built-up grounds, or minor faults that you can diagnose and fix quickly. Regular cleaning, checking the condition of the parts, and setting the right grind all help you avoid downtime. It’s worth knowing the basic symptoms and fixes so you’re not stuck waiting for a technician. A well-maintained grinder is what guarantees consistent espresso and keeps customers moving through the queue.
