I have one of my wetsides that rattles at medium speed, but is OK on slow and on fast. When it rattles, I can actually see the entire wetside assembly turning slowly on the tank wall. It is on a pump less than a year old (though to be fair I'm not sure that I have necessarily kept the correct wetside with its corresponding dry side). I bought the maintenance kit and replaced the screw, propeller and the bushing .... but it hasn't really helped even though there is no obvious signs of wear. Any suggestions would be appreciated.