Excavator Komatsu PW160-7 PW180-7 Excavator Hydraulic Main Control Valve Part Numbers 723-57-17200 723-58-17200 Common Faults Insufficient flow of main control valve, weak and slow machine movements Spool sticking, single function failure and uncoordinated operation Internal leakage of valve block, insufficient pressure during combined operations External oil leakage on valve body, aged and damaged seals and O-rings Wear of valve bore and spool, unstable pressure and jerky