TM 9-2320-366-34-1 2-992 (Continued from previous page) UPPER MAIN CONTROL VALVE PRESSURE/FLOW TEST (CONT)   (5)  Connect hydraulic tester to hydraulic system:         (a)  Connect test hoses to pressure and               reservoir ports of hydraulic tester.         (b)  Connect pressure test hose to left stiffleg               extend hose.         (c)  Connect reservoir test hose to left stiffleg               retract hose. NOTE Steps (6 through 9) require the aid of an assisstant.   (6)  Start engine (TM 9-2320-366-10-1).   (7)  Position PTO switch to on (TM         9-2320-366-10-1).   (8)  Increase engine RPM to 1250-1450 RPM (TM         9-2320-366-10-1).   (9)  Position LEFT STIFFLEG control valve handle         DOWN. (10)  Perform flow test and note reading. (11)  Perform pressure test and note reading. (12)  If flow and pressure are below 12 gpm and         2400 psi, repair or replace upper main         control valve assembly (para 16-83). (13)  If flow and pressure are 12 gpm and 2400-         3000 psi, repair or replace left stiffleg cylinder         (para 16-68). (Continued on next page) WARNING Wear approved eye protection when performing pressure checks. Failure to comply may result in oil getting into eyes.  If oil contacts eyes, seek medical attention immediately. Drop hydraulic pressure to zero before disconnecting any hydraulic hose, tube, or fitting. Failure to comply may result in injury to personnel. Fuel and oil are slippery and can cause falls. Wipe up spilled fuel or oil with rags.  Failure to comply may result in injury to personnel. CAUTION Exercise caution when operating stiffleg. Failure to comply may cause hoses to rub against stiffleg causing damage to equipment. h2.  M1089 LEFT STIFFLEG DRIFTS OR DOES NOT WORK (CONT)