No Humidity, Original Humidistat Broke
Remove the humidity level knob. Remove the two screws holding on the top. Lifted the top and swing to the side. Noting where the two wires go on the humidistat, remove wires. Use a small flat screwdriver to pry back the plastic retainers on one side of the original failed humidistat. Place the new one on, attach the new wires. Replace the knob.