I had the same problem with my FX5 when I took it apart and cleaned it the first time too. Making noise when I hooked the hoses back up, and no water flow. I put it in my fish room sink, filled it with water with the top off, and plugged it in. I realized pretty quickly which tube was the output! (water shooting in my face) I don't know what the problem was, put I know that sometimes with my Eheims it's almost as if there's an air pocket around the impeller that's not allowing it to spin properly - and the 'problem' with the FX5 is that it's on the verge of being too heavy to pick up while it's full and hooked up and give it a shake.
Other than that, I haven't had an issue with this filter. This was my first time cleaning it in the 11 months I've had it set up.
Other than that, I haven't had an issue with this filter. This was my first time cleaning it in the 11 months I've had it set up.

