Abstract: A paper making apparatus is adapted to receive a mixture of liquid and paper fiber on a fiber retaining screen surface operable to drain excess water from the fiber and through the screen, during the formation of a discrete fiber web on the surface. The improvement herein comprises a basin which defines confines for normally retaining the liquids thereby received therein, and has a bottom with generally upwardly extending side walls including a generally horizontally extending ledge adapted to receive the screen in supported relation thereon. The ledge is generally surrounded by a screen positioning wall for locatingly positioning the screen in supported relation on the ledge in draining register above the confines of the basin. The screen positioning wall includes an at least one longitudinally extending opening therein adapted to provide generally open lateral access for grasping an adjacent screen edge in aid of the removal thereof from its supported relation on the basin.