Hi roger, I have a tunze skimmer 9410 dc. The parameters are as follows skimmer is in 5.7inches of water and the control is at the minimum setting. If I pick the air hose hard enough I can reduce the sound. I have opened up the unit and checked the bushes. The bushes are not firm fitting. I have tried to push them in with a dowel however whenever I turn the motor upside down the bushes drop out. Could this be the problem? Thanks Arthur