Fault Phenomenon: Grove GMK5100 during luffing, the dual luffing cylinders move at different rates, causing the boom to bend sideways.

Troubleshooting Process:
– Checked synchronization valve: spool stuck.
– Checked cylinder internal leakage: significant difference in internal leakage between sides.
– Checked hydraulic lines: one line fitting had restriction.
– Cleaned synchronization valve and replaced seals on the cylinder with severe internal leakage.

Root Cause: The hydraulic synchronization valve stuck and one cylinder had excessive internal leakage.

Required Parts: Synchronization valve repair kit, cylinder seals.