DIAGNOSIS The air vent tube in the water reservoir is blocked. This tube equalizes pressure. When blocked, a vacuum forms and stops water flow.
FIX Remove the water reservoir. On the bottom, you'll see the main outlet and a smaller tube—that's the air vent. Use a pipe cleaner or a thin, flexible brush to clear the tube. Blow through it from the top to force out any debris. Rinse the entire reservoir.
IF THAT DIDN'T WORK The one-way anti-drip valve at the base of the water outlet may be stuck closed. This is a small rubber flap. With the reservoir removed, look into the brewer's water intake. Gently poke the rubber flap with a toothpick to ensure it moves freely.
HEADS UP Never use compressed air to clear the vent tube. You can damage internal seals. This blockage is often caused by backflow from overfilling or mineral chunks.