Remove the filter on the side and give it a good cleaning. Then, without putting the filter back in place put the wand of your vacuum against the grill were the filter goes. Cover the exposed are of the grill with your hands (try and get the best seal possible) and suck away. If that doesn't work you will have to take the cover off. Remove the Phillips screws from the bottom of the projector and take off top cover. Get some compressed air and without tilting the can (move the projector not the can) spray away. Also, do a search in the archives as there should be a tutorial with pictures.