I have a problem with my Anova (purchased back in October). The last few times I've used it, every now and then it will sound like metal banging against metal. I've never taken the thing apart, but normally turning it off and on again or moving it around a bit will fix it just fine. Well, I cooked some tenderloin for about 5 hours a few days ago at 140F, and the middle was completely raw. Everything I've seen for tenderloin says about 2-3 hours should be enough for 1-2" thick loin, so I was confused by this. I took out my thermapen and started seeing if it was a calibration issue. First temp I took was ten degrees shy of what the anova was saying. Then I started taking the temp in different spots. Sure enough, at the opposite corner of the cambro, it was off by 30 degrees. Here's a video before I took anything apart. Notice the lack of water movement and the sound at startup (note: the metal on metal sound I have mentioned does not occur in this video) http://youtu.be/2Km3rUSygb8 I also noticed that the water wasn't moving around as much, so I was wondering if the impeller had gone out on it. I took it apart and the impeller looked a bit bent almost. Also, some of the metal probes had a bit of rust on them. Finally, I know my area has hard water, but all the metal on the heating element was scaled a bit. Here's a pic of how the impeller looks... As you can see, it seems a bit off kilter as it were. I messed around with it and you can see where it has scraped against the metal. Right now it's working just fine, I've tested it twice and the temp matches perfectly and the water is circulating. However, i worry that the life of the impeller has been shortened somehow. Anyone experience this before? Since it has a year long warranty and I'm located in Houston (I think the office is in Stafford, TX...fairly close by), I might try e-mailing them and trading it in before the warranty is up. Second question-the scaling? Would it be safe to put some white vinegar/water in a cambro and have the Anova run for a bit in that?