Bulldozer Komatsu D65E-12 D85E-12 D85ESS-2 Main Control Valve Assembly – Part Number 723-63-12101 723-63-12100 Common Faults & Troubleshooting Specific action is weak or not working: Stuck spool in that section, spool/sleeve wear causing internal leakage, damaged O-rings. First measure the outlet pressure of that section to diagnose. All actions are weak: Usually caused by insufficient main pump pressure or a failed main Relief Valve pressure setting. Check system pressure