Our little Onkyo bookshelf stereo had the clicking/popping when we tuned it, meaning changed the radio station. If it has a mechanical dial, it's usually because dust and/or static have gotten in there on the workings. You can try pulling off the knob and blowing some of that compressed, canned air on there to blow the dust off. Also do the same thing on your plugs and speaker connections or wipe them off with a lint free cloth dampened with a little rubbing alcohol.