Abstract: Apparatus for storing and dispensing pigmented marking particles into the development mechanism of a reproduction apparatus. The storing and dispensing apparatus comprises a cartridge including a housing for storing pigmented marking particles, and an elongated opening in the housing through which such marking particles may be dispensed. A cover is removably secured to the cartridge housing to seal the housing opening to prevent contamination of the environment by escape of such marking particles through the opening. The cover, in the preferred embodiment being a flexible sheet member, is selectively removed from sealing relation with the cartridge housing opening and held adjacent to the cartridge away from exposure to the environment when the cartridge is located relative to the development mechanism, whereby marking particles may readily be dispensed into the development mechanism through the housing opening and contamination of the environment is substantially prevented.

Abstract: The adjustment screw that regulates the stroke length of the piston that drives a diaphragm pump is rotated by means of a clutch and "diamond-back" screw structure. By selectively engaging either of two oppositely oriented one-way clutches, one of two respective associated nuts that ordinarily rotate freely on the "diamond-back" screw is blocked from rotation when the screw moves longitudinally in one direction. Thus locked, the nut compels the "diamond-back" screw to rotate, thereby turning the adjustment screw with which it is connected in order to produce the desired increase in piston stroke length.