Sometimes you have to open things up to clean them. It doesn't really take much to convince me to do this. Even though my knowledge of circuit design is fairly low, I enjoy looking at the little cities laid out in solder, resistors and ic's on that green board.
This is a PSone, model no SCPH-101, made in December of 2000. It really wasn't that dirty but there was some dust and hair I couldn't get to without opening up the case.
Six screws hold it shut, one of them under a warranty seal. These were actually tough screws to loosen, they require a small phillips and a bit of effort.