I have the first generation MP40w. It is problaby 4 months old but I just started using 2 weeks ago. It worked fine for the first week or so. Then at about 2 weeks it started with the inconsistent speed. It will run full blast for about 10 min. then slow all the way down for about 10 min. then it start the cylce all over. It stays doing this all day. I know that I have it in the contant speed mode because the light on the controller stays green at all times, whether it slows down or is in the middle of changing speeds. Any help is much appreciated. Thanks