This is the sound of water draining back from the hot plate into the internal tubing. It's usually normal, but excessive noise indicates a clog.
- After brewing, unplug the machine and let it cool completely.
- Remove the carafe and brew basket.
- Check the small exit hole in the brew basket area where coffee drips out. Clear any coffee grounds or debris.
- Examine the warming plate surface. Wipe off any coffee residue or mineral deposits.
If that didn't work: The internal water tubes are likely restricted by mineral scale.
- Mix one part white vinegar with two parts water.
- Pour the full mixture into the water reservoir.
- Run a full 12-cup brew cycle without coffee.
- Run two cycles with clear water to rinse.
Heads up: Perform this descaling process every 3-6 months if you use hard water. Scale buildup reduces heating efficiency and causes strange noises.