keurig classic only brews a tiny bit of coffee then stops, like a partial cup

The exit needle is clogged with coffee grounds. This blocks water flow.

Fix:

1. Unplug the brewer.
2. Press the "PRESS TO OPEN" button, grasp the top of the K-Cup Holder, and push up on the bottom from underneath to remove the assembly.
3. Remove the funnel by pulling on it until it releases.
4. Insert a paper clip into the exit needle (located on the inside bottom of the holder) to loosen the clog and push it out.
5. Rinse the K-Cup Holder under a faucet. It is dishwasher safe.
6. Reassemble the funnel and holder, and snap it back into the brewer.

If that didn't work: Mineral scale buildup in the internal plumbing can also restrict flow. You need to descale the brewer. Use 8 ounces of undiluted white vinegar in the hot water tank, run a brew cycle without a K-Cup, let it sit for 30 minutes, then flush with multiple tanks of bottled water.

Heads up: The entrance needle above the K-Cup Holder does not require cleaning. Do not put your fingers in the K-Cup chamber.