The knob one turns to set the humidity level was removed. The two screws holding the top on were removed. The top was lifted and swung to the side. After noting which of the two wires went where on the humidistat the wires were removed. Small flat screwdrivers were used to pry back the plastic retainers on one side of the original failed humidistat. The new one was put in place, the two wires were reattached. The knob was replaced. The top was positioned and its two retaining screws replaced. A magnetic phillips screwdriver was handy but not necessary. Piece of cake! Someone with ten thumbs could do it!! Thanks for the prompt courteous attention to the returned erroneous part! Dealing with partselect. Com was a pleasure. . . . . . Thanks!! P. S. The dehumidifier works like new now!!