I have two in my tank and they are great pumps. I've never had one fail on me. I have 6000s now and had 4000s for 4 years of continuos running with no problem. I would bet that you might have a broken impeller shaft. They are ceramic to keep the noise and heat down, but are very brittle. Undo the screw in front and CAREFULLY remove the shaft, then impeller. They are very quiet pumps. If it's new return it.