I have a new Eheim 2217 canister (its only a few months old) I just cleaned it the other day, and decided to look at the impeller and make sure it wasn't dirty. This was my first time doing this part, because I did not have a need to do so previously. I put it back together, primed it, and there has been a loud rattling/grinding noise ever since. I know it is not due to air. I know what that sounds like, and have sat and gently tipped it to remove all the air. I have checked every connection, and they all seem fine. The hoses are a tad dirty ( I lack brushes for now) but I can still see through them, and have rinsed them. I am really bummed because this filter ran soooo incredibly quietly (first filter to ever do so as advertised!) before this last cleaning. I bought a new shaft, thinking maybe mine was warped, but it hasn't helped. I have noticed the hole in the impeller might be more oval shaped, however it has been rattling for two weeks, so this may be a result of the grinding, not a cause. I ordered a new impeller anyways, but am worried what to do if the sound persists after I put in the new impeller. Any information about this problem would be awesome!