You can usually recognize freezing damage by the slightly raised rubber sleeve of the water tank. Open the bottom plate of the coffee maker and disconnect the rubber hose coming to the lower end of the boiling element. Open the screws on the water tank and remove the water tank by pulling lightly.
The frozen water pushes the lower end of the heating element away from the boiler tube and the coffee maker starts leaking underneath. Remove the lower end of the resistor from its bracket and loosen the lower end nut. The lower end consists of a rubber gasket that seals the boiling tube by pressing two metal plates together. There is a hex bolt inside the resistor and an 8 mm nut underneath.
Push the base section of the resistance back into the boiler tube so that approx. 5 mm of the boiler tube remains visible after the base. Tighten the bottom nut while holding the bolt in place with the hex key from the inside of the resistor. See that the hose connector of the water tank goes in the right direction. Attach the resistor to the lower end bracket and assemble the Moccamaster coffee maker.