the grinder is making a horrible loud screeching noise when it runs, sounds like metal.

Diagnosis

The loud, metallic screeching sound emanating from the Breville Oracle Jet BES750BSS integrated grinder is typically caused by "burr collision." This occurs when the upper burr makes direct contact with the lower burr. Because the Oracle Jet uses a high-torque motor to drive the grinding process, any misalignment or foreign object creates a high-frequency vibration and friction that sounds like a scream or a grinding wheel. This most commonly happens due to one of three reasons: a foreign object (like a small stone or unroasted "hard" bean) has lodged in the teeth, pushing the burrs out of alignment; the grind setting was adjusted to an extremely fine level while the motor was not running, causing the burrs to overlap; or the upper burr has loosened from its mount, allowing it to shift laterally during rotation. You can confirm this by turning the machine off and manually rotating the upper burr; if you feel a hard stop or a "crunch" before the burr completes a full rotation, there is a physical obstruction or misalignment.

How to Fix It

To resolve the screeching and prevent permanent damage to the motor or the burrs, follow these precise steps:

1. Power Down: Immediately turn off the machine and unplug it from the wall outlet. Do not attempt to "grind through" the noise, as this can strip the drive gear.
2. Clear the Hopper: Remove the bean hopper. Use a vacuum cleaner with a narrow nozzle to suck out all remaining beans and loose grounds from the throat of the grinder.
3. Remove the Upper Burr: Twist the upper burr carrier counter-clockwise to unlock it and lift it straight up and out of the housing.
4. Inspect for Debris: Examine the teeth of both the upper and lower burrs. Look for small pebbles, pieces of plastic, or "petrified" coffee oils that have hardened into a rock-like substance. Use a stiff nylon brush or a toothpick to pick out any debris lodged in the grooves.
5. Reset the Grind Setting: Rotate the grind size dial to a medium-coarse setting (around 15-20 on the dial). This creates a larger gap between the burrs, ensuring they cannot touch during the restart.
6. Reinstall and Seat: Carefully drop the upper burr back into place. Ensure it seats perfectly flush. Lock it by twisting clockwise until it clicks firmly into position.
7. Test Run: Plug the machine back in and run the grinder for 2 seconds. If the noise is gone, slowly adjust the grind setting back to your preferred level, listening closely for any return of the screeching sound.

If That Didn't Work

• Deep Clean the Lower Burr: If the screech persists, the lower burr may be clogged with compacted oils. Use a specialized grinder cleaning tablet (like Urnex Grindz) by pouring them into the hopper and running the grinder. This pushes out compacted debris that a vacuum cannot reach.
• Check for Burr Wear: Inspect the edges of the stainless steel burrs under a bright light. If you see "silvering" or flat spots on the teeth, the burrs have been physically damaged by a foreign object and must be replaced. Contact support for the specific burr assembly kit for the BES750BSS.
• Verify Dial Calibration: If the noise only happens at the finest settings, your dial may be out of calibration. Reset the machine to factory defaults by powering off, holding the "dose" button, and powering back on to see if the electronic limiters reset.
• Inspect the Drive Shaft: With the upper burr removed, use a flashlight to look down the shaft. If the shaft appears bent or wobbles significantly when rotated by hand, the internal bearing has failed, requiring a professional technician to replace the motor assembly.

Heads Up

• Avoid "Zeroing" the Grinder: Never adjust the grind setting to the absolute minimum while the machine is off; always leave a small gap to prevent the burrs from locking.
• Bean Quality: Only use high-quality, roasted coffee beans. "Natural process" coffees often contain small stones or twigs that can cause this exact screeching issue.
• Avoid Oily Beans: Extremely dark, oily roasts can create a sticky residue that attracts debris, eventually causing the burrs to "clog" and shift alignment.
• Regular Vacuuming: Every 30 days, remove the hopper and vacuum the burr chamber to prevent the buildup of "fines" which can migrate into the mechanical housing.