DIAGNOSIS The single-serve water inlet is clogged with mineral scale or coffee grounds. This restricts flow, causing water to overheat and not brew properly.
FIX Unplug the unit. Remove the water reservoir. Look inside the machine where the reservoir sits. You'll see a small black rubber grommet with a hole—that's the inlet. Use a stiff bristle brush (a clean toothbrush works) and white vinegar to scrub that grommet and the hole behind it. Then fill the reservoir with a 50/50 mix of white vinegar and water. Run several single-serve cycles without a pod or cup to flush the internal line.
IF THAT DIDN'T WORK The problem might be upstream. Check the puncture needle in the center of the single-serve basket. Use a paperclip to gently clear any compacted coffee grounds from the tiny holes in the needle.
HEADS UP Never use descaling chemicals stronger than vinegar or citric acid. Harsh chemicals can degrade the internal silicone tubing.