The cold water valve sticks on my Hamilton Beach Model 87330 water dispenser. When I release the cold water button, the button SHOULD immediately pop back out and the water flow immediately stop. Instead, however, the button sticks in the down position or very slowly comes back out, resulting in overflowing cups and a wet kitchen floor. Sometimes it takes 10 sec or more to get it to shut off. The unit is about 15 months old.