I decided to take my Ice Cap 3k apart this morning to clean it. It ended up still being very clean, just the mesh covers were collecting dirt. I put it all back together nice and tight and left the covers off. To my surprise, it is now perfectly quiet. I have a hunch the noise I was hearing since the start may have been the various pieces not pushed all the way together, or maybe the covers were causing it. I don't know, but now it's silent.