A machine comprises an enclosure; a plurality of parts within the enclosure; and a visual conduit for providing a view inside of the enclosure for detection of visible signs of failure of the machine. The concept of a visual conduit encompasses a broad variety of devices including cameras inside the enclosure that provide images of the interior of the enclosure and alternatively selective transparency or translucence of the enclosure relative to at least some of the parts of the machine housed within the enclosure.