Product review (5 stars): A great kit!
Great kit.  We purchased a home recently with the 560 humidifier.  I figured I'd freshen it up since it was installed apparently in 2001.  The filter looked bad, and the other components were similar.  I'm certain no one has touched this thing in the last 14 years.  This kit brought me right back to new condition and everything seems to work great.  Water is flowing much better.  I've now dialed back the flow of water into the unit so there isn't as much waste water.  I didn't realize there was a filter  in the solenoid input.  Glad this kit came with one because when I pulled mine it was clogged.  This was probably affecting the flow of water.

Installation is a breeze, but if you want help check out: http://video.aprilaireparts.com/v/1332271514/aprilaire-600maintkit-humidifier-model-600-maintenance-kit/