Abstract: A toner container receiving apparatus has a sump and a sump opening with box-like upwardly extending vertical walls around the sump opening. A toner container includes box-shaped downwardly extending walls which fit around the sump walls when the container is positioned over the sump. A flexible cover is movable from a covering position above the box-shaped walls through a curved path to a position alongside an exterior vertical wall of the container. A lever on the receiving apparatus is movable to a vertical position and is coupled to structure which locks the container to the sump during that movement. A handle connected to the cover is positioned to fit into a slot into the lever and prevent moving of the lever away from its vertical locking position until the cover has been moved to its covering position. The cover is flexible enough to move through the curved path but stiff enough to be pushed back to its covering position.