SEAL-O-RING 1257001 - Caterpillar

Probable Causes
The lift control lever and/or the position sensor may be worn or damaged.
The control current to the solenoid is incorrect.
The main control valve is contaminated or damaged.
The load check valve is not closing because the spring is weak or broken,or because there is dirt or debris in the check valve.Note: Ensure that there are no active diagnostic codes for the hydraulic system.Recommended Actions
The Lift Control Lever And/Or The Position Sensor May Be Worn Or Damaged
Refer to Testing and Adjusting, "Position Sensor for the Joystick Control (Electronic Technician) - Calibrate" in this manual.The Control Current To The Solenoid Is Incorrect
Refer to Testing and Adjusting, "Position Sensor for the Lift Linkage (Electronic Technician) - Calibrate" in this manual.Note: Ensure that the strainer is present in the filler tube before adding the recommended hydraulic oil.The Main Control Valve Is Contaminated Or Damaged
Refer to Testing and Adjusting, "Main Control Valve (Electronic Technician) - Calibrate" in this manual.The Load Check Valve Is Not Closing Because The Spring Is Weak Or Broken,Or Because There Is Dirt Or Debris In The Check Valve
Refer to Testing and Adjusting, "Lift Cylinder - Isolation and Drift Check" in this manual.Refer to Testing and Adjusting, "Tilt and Tip Cylinder - Isolation and Drift Check" in this manual.
Ensure the machine is on a level surface.
Raise the blade approximately 300 mm (12 inch) off the ground. Place the lift control lever into the HOLD position. Apply the parking brake. Shut off the engine.
Shut off the engine. Watch the lift cylinder rods for movement (cylinder rods retracting).