I just got a new Maxijet 900 "Pro" and the thing is buzzing like crazy. I've had 2 in the past that were a bit nosy for a day or two but then quieted down. This once has been up for a week and continues to make enough noise I can hear it clear across my house. Anyone have experience with this? Do the newer ones tend to be noisier these days or is this one just a dud?