The exit needle is clogged with coffee grounds, or the brewer needs descaling.
First, clear the exit needle:
- Remove the K-Cup pod holder assembly.
- Detach the funnel.
- Find the exit needle on the inside bottom of the pod holder.
- Insert a straightened paper clip into the needle to loosen grounds.
If that doesn't fix it, descale the brewer. Mineral scale buildup is the other main cause. Run the full descaling procedure using Keurig Descaling Solution.
Heads up: If you've descaled twice and it still brews partial cups, contact Keurig Customer Service.