So i recently obtained a fluval 404 i know a bit old but very good condition and it was in the package for the 90 gallon tank i got. I set it up and it was running the first night, nice and quiet, a good flow, was great, until the morning it stopped running for some apparent reason. i got it up and running again, running for a good 8 hours, when i came back into my apartment it literally stopped pumping right in front of me. i took a look at the magnet looks very clean to me. What could be the cause of this? Any help would be appreciated.