Diagnosis
A foreign object (like a rock from beans) or a hardened chunk of old coffee is jammed in the ceramic burr grinder.
How to Fix It
Clear the grinder chamber immediately.
1. Turn the machine off and unplug it.
2. Open the bean hopper and remove all beans.
3. Use the provided plastic cleaning tool (looks like a small brush/pick) to manually rotate the top burr and dislodge debris. You can access it through the opening.
4. Vacuum out any loose particles from the hopper and chute.
If That Didn't Work
The noise could indicate a worn-out or broken grinder bearing. If clearing debris doesn't stop the noise, the grinder unit itself likely needs replacement by a technician.
Heads Up
Always visually inspect beans before pouring them in. A single small stone can crack the ceramic burrs, which is a very expensive repair. Consider using a bean sieve.