The document provides instructions for disassembling and assembling the boom cylinder of a Caterpillar 301.7CR Mini Hydraulic Excavator. The disassembly procedure involves removing seals and internal components from both ends of the cylinder. The assembly procedure describes installing seals and components in the reverse order of disassembly. Tools required include a cylinder repair bench, spanner wrenches, and sockets. Safety precautions are provided regarding hydraulic pressure during disassembly.