I changed the bearings and the retainer with the complete box, and after a while I began to whistle when I centrifuged. Could you help me that can be. thanks.

Friend, when changing bearings and seals, you also have to change the axle, if you do not change this, it is very common for the rollers to have run over again by the water that filters between the shaft and retainer. regards

It may also be that the flexible clutch washer is not lubricated.