DIAGNOSIS The water is passing through the K-Cup too quickly. This is almost always because the exit needle (the one in the bottom of the K-Cup holder) is clogged or the piercing process is incomplete.
FIX Unplug the machine. Open and close the K-Cup handle a few times, watching the top needle. Then, lift the handle and look at the small exit hole in the bottom of the pod chamber. Use a paperclip to gently clear that hole of any old coffee grinds or scale. Soak the entire K-Cup holder assembly (the removable funnel) in warm, soapy water.
IF THAT DIDN'T WORK Check the brew temperature. If it's too low, extraction is poor. To test, run a 6oz cycle without a pod into a mug. Use a kitchen thermometer immediately. It should be between 192°F and 197°F. If it's cooler, the thermostat might be failing, which is a bigger fix.
HEADS UP The 'Strong' button only makes the machine pause mid-brew to steep longer—it doesn't increase temperature or pressure. If the exit hole is partially clogged, that extended steep time doesn't matter because the flow is still messed up.