the grinder on my delonghi magnifica s is making a horrible loud screeching or grinding noise, is it broken?

Diagnosis

The loud, metallic screeching or high-pitched grinding noise in your De'Longhi Magnifica S is typically caused by "foreign object intrusion." This occurs when a non-coffee object—such as a small pebble, a piece of hard plastic from a bean bag, or an exceptionally hard, oil-baked coffee bean—becomes wedged between the upper rotating burr and the lower stationary burr. Because the Magnifica S uses a high-torque motor to drive the steel burrs, the object is forced into the gap, creating a friction-based screech as the motor struggles to rotate the assembly. In some cases, this can also be caused by "burr starvation" or a partial jam where the beans are not feeding correctly, causing the burrs to spin against each other without the cushioning effect of the beans. You can confirm this by listening for a change in the motor's pitch; if the noise is rhythmic and accompanied by a slight slowing of the motor speed, something is physically obstructing the grinding path. If the noise is a constant, high-frequency whine, the object is likely trapped in the outer edge of the burr radius.

How to Fix It

To clear the obstruction and restore silent operation, follow these precise steps. Do not attempt to run the grinder while you are cleaning it to avoid injury.

1. Disconnect the machine from the power outlet immediately to prevent the motor from engaging unexpectedly.
2. Empty the bean hopper completely. Use a vacuum cleaner with a hose attachment to suck out all loose beans and fragments from the hopper area to ensure you have a clear line of sight.
3. Remove the bean container lid. Using a strong flashlight, inspect the center of the grinder throat. Look for any visible pebbles, silver-colored metallic shards, or unusually light-colored debris.
4. If the object is visible, use a pair of long-reach needle-nose pliers or a vacuum with a narrow crevice tool to extract the debris. Do not push the object further down into the burrs.
5. If the object is wedged deep, you must manually rotate the burrs. With the power off, use a sturdy toothpick or a small plastic probe to gently nudge the upper burr clockwise. If you feel a hard stop, carefully wiggle the probe to dislodge the fragment.
6. Once the debris is removed, take a handheld vacuum and thoroughly clean the area around the burr edges to remove any "dust" created by the grinding of the foreign object.
7. Plug the machine back in and run a "grind only" cycle (if your model allows) or brew a single shot to verify the noise has subsided.

If That Didn't Work

• Adjust the Grinder Dial: If the noise persists, the burr gap may be set too tight. While the grinder is running, slowly turn the grind adjustment dial (located inside the hopper) to a coarser setting (a higher number). This increases the gap between the burrs and can often "spit out" a trapped fragment that was previously wedged.
• Deep Clean the Infuser: Sometimes the noise is actually coming from the brewing unit (infuser) rather than the grinder. Remove the water tank, open the side door, and slide out the infuser assembly. Rinse it under warm water and ensure the O-rings are lubricated with food-grade silicone grease. A dry infuser can sometimes mimic a grinding sound during the coffee delivery phase.
• Check for Bean Oil Buildup: If you use very dark, oily beans, a "plug" of oil-soaked grounds can harden into a concrete-like mass. Use a specialized grinder cleaning tablet (like Urnex Grindz) or a small amount of dry, uncooked rice to run through the grinder. This absorbs the oils and pushes out stubborn debris.
• Inspect the Drive Gear: If the screeching is accompanied by a plastic-on-plastic clicking sound, the drive gear connecting the motor to the burrs may be stripped. This requires a full teardown of the chassis to replace the gear assembly, which is a complex repair involving the removal of the outer casing.

Heads Up

• Avoid Flavored Beans: Never use caramelized or sugar-coated flavored beans in the Magnifica S. The sugar melts during the roasting process and creates a sticky residue that glues beans together, leading to jams and the screeching noise you are experiencing.
• Bean Selection: Avoid "espresso blends" that contain corn or soy fillers, as these are often harder than coffee beans and can damage the steel burrs.
• Dial Adjustment Rule: Only adjust the grind setting dial while the grinder is actually running. Turning the dial while the motor is off can put undue pressure on the burr assembly and potentially crack the plastic housing.
• Regular Vacuuming: Every 500 cups, vacuum out the bean hopper and the area around the burrs to prevent the buildup of "fines" (micro-dust) which can contribute to friction and noise.