Not a cleaning issue. It's an mp40 issue. They are dead quite when you first buy them. Then after some un predefined time 2 weeks to 3 months....they turn noisy. Original was about 3months, bought second Westside and threw old one away since cleaning it did not fix issue. Tried to make some changes to it but ultimately got frustrated and tossed it. After 2weeks on second wetside it started humming again. Bought 3rd Westside still in box as backup on 2nd set. Did research and found plenty of people complaining about the noise. So there is nothing to do about it. Maybe a solution would be to get mp60 and run at lower power, but to me that's ridiculous. Anyway. I like the clean look, so that is the only reason I haven't pulled them off.
It really depends on what settings you have them on and power needed if you hear anything. When I had the mp40 on my 40 gallon frag tank running at 20 to 30% power. It's silent. When you put it on 255gallon tank and need to move more water by increasing power. It's noisy at my house.
They are real quite in many applications, just not in my case where I'm trying to move more gph in sps dominant tank with random gusts