The Media Select Switch should be in which position during printing?
It depends on the file composition. Although the switch is marked for media weight, we have found it is easier for users to look at the composition of their file in terms of blacks and halftones/screens/grays. The Media Select Switch should be in the down/off position when printing solid blacks. If printing halftones/screens/grays, the switch should be in the up/on position. When printing files containing equal amounts of blacks and halftones, try both settings and choose the one which gives the best result for you file.
