GROMMET AND TUBE IM Assembly WR29X24766

This refrigerator is 2 years old. Ice maker stopped making ice and after replacing the thermistor and ice maker found a badly blocked and frozen Tube assembly. Was very difficult to melt ice and clear the tube but it did clear and i reassembled and ran. After 1 cycle of im making ice cubes it stopped Making ice and water forced out back of refrigerator around tube seal and Tube was frozen closed again. Is there a heater in the refrigerator body that May be defective? What else could cause freezing after 1 cycle?

Grommet and fill tube for ice maker how does it pull out want to see if line is frozen or blocked will not come it's nest