Advice on powerheads

[hillegom]

Any calcium deposits on it?
Try submersing in vinegar overnight, non running, to see if that helps.

[bignose]

I had the same thing happen to one of my k4's. I took it out of my tank and I'm replacing it soon.

edit - I cleaned the pump and still the same sound.

[toytech]

They are so cheap , get some new ones .