There is a knocking noise. I have unplugged and thawed ice. After reinstalling, most of the time it will refill and freeze on set of cubes. However, it will not eject the cubes which results in the knocking noise of the gears trying to eject the cubes. I am not sure if there is some sort of thermostat that is not working to engage a heating element. Any thoughts or suggestions would be welcome. Thanks in advance.