The CD laser is infra-red, it will penetrate quite a lot of dust in the optical system. The SACD laser is red, which is much more easily blocked and dispersed by dust, especially on hybrid discs. Loose accumulations of dust can be removed by opening the tray and spraying two 1-second bursts from a can of Air Duster into the unit down the centre of the tray. Sticky deposits can sometimes be removed from the optical system by your dealer using a small amount of alcohol. More serious contamination will require replacement of the laser module – please contact your dealer or distributor to arrange this. Tobacco smoke and dust from construction work are among the worst contaminants.