DIAGNOSIS Water is escaping from an internal seal or hose. The two most common leak sources on the K-Duo Plus are the internal water tank connection or the drain hose from the drip tray area.
FIX Pull out the drip tray and the removable drip tray cover. Dry everything thoroughly. Run a brew cycle while watching closely inside that empty drip tray compartment. Look for a small, clear plastic hose coming from the back—that's the drain hose for overflow. If you see water dripping from its connection point or from a split in the hose, that's your leak.
IF THAT DIDN'T WORK The leak might be from where the reservoir attaches. Remove the water tank and inspect the black rubber gasket on the bottom of the tank and the matching receiver on the machine. Clean both with a vinegar-dampened cloth and ensure the tank clicks firmly into place.
HEADS UP If the leak is truly from the machine's underside, it's often the internal water pump or a tube connection that has vibrated loose. This requires disassembly and is not recommended unless you're very comfortable with appliance repair. A persistent internal leak can damage the heating element.