My wife's comp has a pair of Logitech z625 speakers. They sound fine, but they're afflicted with obnoxious potentiometer scratching that I can only briefly subdue with Deoxit. Is there a better fix?

So my Swan M200 active monitors did something strange yesterday. All of a sudden, they began to emit a loud hum.<BR><BR>The hum comes from both speakers, and is present whether or not the line in is ...