The 4558 opamps are failing, these are responsible for redbook audio from the CD drive and cause the symptoms you describe. Look at IC203 in particular on the board and see if the text on the chip surface looks faded compared to the others, or if any other instance of this chip elsewhere looks 'cooked.' There's one around/under the power supply/voltage conditioning circuit that gets overheated sooner than the rest. You're probably better off replacing all of them, they're 8-pin surface mount chips. If a capacitor replacement hasn't been performed at this point you should expect corrosion from leaked electrolytic as well.