This document provides instructions for releasing hydraulic pressure and disassembling/assembling the piston pump on a 259D Compact Track Loader. It outlines the required tools and multi-step procedures for disconnecting hoses and electrical connections, removing mounting bolts, and disassembling internal pump components like valves, cartridges, seals and bearings. Reassembly follows the reverse order and includes cleaning, inspecting and replacing components as needed.