I listed a DP-385 earlier that was making a lot of noise and was being used as a sump pump. Well, I took it apart and my 3 year old son noticed that the impeller blades were moving on the magnet shaft. I took my other one apart and saw that it was firmly fixed. So, I glued the other one together and now it is quieter than my "quiet" DP-385. Unreal!! He gets a double scoop of ice cream for that one!!