My home stereo speakers are sometimes fuzzy and can be fixed by twisting the speaker balance knob back and forth quickly a few times. I think the contacts need cleaning (does this sound logical?). If so, is this difficult to do? How should this be done (it doesn't seem as though it should be too complicated). Can WD 40 be used, or should I shell out $10 or so for Radio Shack's little can of contact cleaner?