IF it is related to the pump/motor than it is either something about the motor itself of something in the impellar. A pump seal failure could lead to this over time, or IF you do not turn you pump/motor OFF when taking the filter out, you could have sucked something into the impellar. I really can't tell you some of the things that we have removed from the impellar of "noisey" motors, but one of them was "Barbie's slipper", and the most common is leaves.