IBM seemed to have a fondness for black foam in their equipment (typewriters to RS/6000 and PS/2 systems), which I suspect was used for noise dampening. Unfortunately, the foam comes off and leaves black grime along the airflow channels. It also deteriorates, so when confronted, it's a sticky, gooey mess that is hard to remove. It's not a pleasant task to get it off, but I am willing to do it. My concern is that the placement of the foam was also used for airflow regulation. With it gone, the system may overheat. Has anyone had any experience with this stuff? Kirill