HOSE AS 6Y9550 - Caterpillar

Introduction
The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the solution that is identified below.Problem
Caterpillar has received reports of low or erratic hydraulic power complaints on M300D Wheeled Excavators and M300D Wheeled Material Handlers. This loss of hydraulic power in certain instances has been caused by a loose 165-9407 Plug that is on the 253-7766 Pump Control Valve Gp (Load Sensing). This load sensing valve is installed on the 286-7002 Pump Control Valve Gp (Main Pump Controller) .Solution
Caterpillar is investigating the root cause of these failures. More information is needed in order to better understand the cause of these failures. If a field report of low or erratic hydraulic power is received, follow the following steps in order to resolve the issue.
Illustration 1 g01708319
Measure and record the LS signal limiter and main pump pressures. Refer to Testing and Adjusting, RENR9465, "Relief Valve (Signal Limiter) - Test and Adjust".
If the main pump or LS signal limiter pressure is out of the specified pressure, check the torque of 165-9407 Plug (Load Sensing) (1). Place a mark on plug (1) and the housing. Set a torque wrench to 40 N m (30 lb ft). Turn the plug with the torque wrench until the wrench clicks. Check the position of the mark. If the mark moved, the plug was loose. Torque the plug again to a torque of 100 N m (74 lb ft). Recheck the pressures.
If the pressure is still out of the specified pressure or erratic, remove 6E-5060 Cap As (2). Check the torque of 6E-1607 Sealing Locknut (3) by placing a mark on locknut (3) and plug (1). Set a torque wrench to 14 N m (10 lb ft). Turn locknut (3) with the torque wrench until the wrench clicks. Check the position of the mark. If the mark moved, locknut (3) was loose. Torque locknut (3) again to a torque of 22 N m (16 lb ft). Recheck the pressures.
If plug (1) and locknut (3) were not adjusted attempt to perform a main pump calibration by using ET.
If the calibration procedure of the main pump fails, remove the 253-7766 Pump Control Valve Gp from the main pump controller. Inspect the valve for broken internal components, or damaged surfaces of the piston.
Open a DSN ticket in order to communicate to Caterpillar whether torquing the plug or locknut again resolved the issue. Open a DSN ticket in order to communicate whether a component inside the 253-7766 Pump Control Valve Gp failed. Document and attach to the DSN pictures of the failed hardware and the part number that was ordered in order to resolve the failure.A final fix will be communicated when the root cause is identified and the issue is resolved.