unused cubes form a solid block in the bin

If the bucket is forming a large block of ice, either the icemaker is leaking and needs to be replaced (you’ll see a mound of ice in the bucket directly below the icemaker if this is the case), or your freezer is going into defrost too long. There is a 1″ round defrost sensor clipped onto the top of the silver evaporator coils that should shut the defrost cycle off if it’s getting too warm. This sensor would need to be replaced. You’d need to take everything out of the freezer and remove the entire back wall panel inside the freezer to see the silver coils and replace the thermostat sensor.