Fault Phenomenon: Hitachi KH300 severe veering when traveling straight, requiring constant steering correction.

Troubleshooting Process:
– Checked pressures on both travel motors: significant pressure difference.
– Checked travel brakes: one side brake not fully releasing.
– Checked travel pilot valves: inconsistent spool travel.
– Adjusted pilot valve travel and cleaned brake control valve.

Root Cause: The travel pilot control valve spool was stuck, causing uneven flow distribution between sides.

Required Parts: Pilot valve repair kit.