Diagnosis
The most common cause is using the wrong grind size or not enough coffee. The machine's spray head needs a specific resistance to saturate grounds properly.
How to Fix It
Use a medium-coarse grind, not pre-ground fine drip grind. For a full 10-cup carafe, use at least 10 tablespoons (a full Ninja scoop is 1 tbsp). Pack the grounds loosely and level them in the filter basket.
If That Didn't Work
Check the brew basket spray head for clogs. Remove the basket, lift out the silicon seal, and look for tiny holes. Soak it in vinegar to clear any mineral deposits blocking water distribution.
Heads Up
Never use a fine espresso grind—it will compact, restrict water flow, and cause overflow into the drip tray, resulting in weak coffee.