Please see below for the Oberdorfer N4000S3 exploded view and parts list to help find the correct part numbers to each replacement part if you're only needing specific items and not having to replace the pump. If you feel a repair kit is all that is necessary to return your Oberdorfer N4000S3 Bronze Gear Pump back to factory flow specifications, please see the bottom of the page under the "Related Products" section for the N4000S3 repair kit.