Is it worth saving to you? If so dilute some citric acid to the proper ratio and let it sit in the water reservoir for a few hours. Turn the machine ON and see if it starts to flow through. If so, let about half the mixture go through and turn it OFF to sit a bit longer to ensure maximum effectiveness. Then turn ON again and let brew cycle finish. Then run several fresh water cycles through and taste the water often as citric acid tastes like sour salt.
I use a heaping teaspoon per quart of very warm water and stir until fully dissolved. Of course more can be used for quicker results, but I prefer to use less unless more is really necessary.