it's making a loud grinding or vibrating noise, way louder than the normal pump sound, only on the hot settings.

Diagnosis

The loud grinding or vibrating noise you are hearing during hot brew cycles is a symptom of "pump cavitation." This occurs when the internal water pump is unable to pull a consistent stream of water from the reservoir, causing it to suck in air bubbles or struggle against a vacuum. Because the pump is spinning at high RPMs without the lubricating and cushioning effect of a full water column, it creates a violent vibration that resonates through the plastic chassis of the machine. This typically happens on hot settings because the heating element increases the water temperature at the intake point, which can cause air pockets to expand or mineral deposits to shift and block the narrow aperture of the water filter. If the noise is absent during "Rapid Cold Brew" but present during "Classic" or "Rich" hot brews, the issue is almost certainly a pressure differential caused by a clogged filter or a displaced O-ring in the reservoir assembly, preventing the pump from achieving a prime seal.

How to Fix It

To resolve the pump cavitation and eliminate the grinding noise, follow these precise steps:

1. Power down the unit and unplug it from the wall outlet to ensure the heating element is not active.
2. Lift the water reservoir out of the machine. Locate the water filter assembly (the plastic housing containing the charcoal filter).
3. Remove the filter housing and inspect the blue rubber O-ring seal at the base. If the seal is pinched, twisted, or has a hairline tear, it will allow air to leak into the pump line, causing the vibration. Replace the seal or reseat it firmly.
4. Remove the charcoal filter cartridge from the housing. If the cartridge appears grey or slimy, it is saturated with minerals and is restricting flow.
5. Perform a "Prime Flush": Fill the reservoir with distilled water (no filter). Place a large travel mug on the drip tray.
6. Select the "Classic" brew style and the "Large Cup" size. Start the brew cycle. This forces the pump to push out any trapped air pockets without the resistance of a filter.
7. Once the noise subsides and a steady stream of water flows, reinstall a fresh, soaked filter cartridge. Ensure the cartridge is fully submerged in water for 10 minutes before installation to remove air gaps within the charcoal media.

If That Didn't Work

• Perform a Deep Descale: Mineral buildup (calcium/magnesium) inside the internal thermoblock can narrow the water path, forcing the pump to work harder. Fill the reservoir to the MAX line with a 50/50 mix of white vinegar and water. Run a "Clean" cycle or a full "Travel Mug" brew with no coffee. Run two additional cycles with plain water to clear the vinegar scent.
• Check the Reservoir Valve: Inspect the spring-loaded valve at the bottom of the water reservoir. If a piece of debris or a coffee bean fragment is lodged in the valve, it won't open fully, starving the pump of water. Gently press the valve with your finger to ensure it snaps back instantly.
• Air Lock Reset: If the machine was run dry, an air lock may be trapped in the internal tubing. Remove the reservoir, fill a small cup with water, and carefully pour it directly into the intake hole where the reservoir sits while simultaneously starting a brew cycle. This "shocks" the pump into priming.
• Inspect the Water Line: Check the area beneath the reservoir for any leaks. If water is dripping from the bottom of the machine during the noise, a hose clamp has likely slipped, allowing the pump to pull air from the leak rather than water from the tank.

Heads Up

• Filter Maintenance: Replace your charcoal filters every 60 days or every 60 tank refills. Using an expired filter is the #1 cause of pump strain and noise in the XL series.
• Water Quality: If you live in a hard-water area, avoid using unfiltered tap water. This leads to "scaling" in the heating element, which eventually burns out the pump motor.
• Avoid "Dry Brewing": Never start a brew cycle if the water level is below the minimum line. Running the pump dry for even 10 seconds can cause permanent wear on the pump seals.
• Storage Tip: If the machine will be unused for more than two weeks, empty the reservoir and remove the filter to prevent biofilm buildup that can clog the intake valve.