TM 10-3930-669-20 10.  HYDRAULIC MAST LIFT SPEED SLUGGISH (CONT). KNOWN INFO Lift cylinder hose(s) OK. Lift control cable OK. POSSIBLE PROBLEMS Hydraulic pump faulty. Stack valve faulty. KNOWN INFO Transmission operates. Hydraulic fluid level OK. Hydraulic tank to pump suction hose OK. Hydraulic pump OK. Stack valve OK. POSSIBLE PROBLEMS TEST OPTIONS Pressure test. STE/ICE-R #51. REASON FOR QUESTION If hydraulic pump is faulty, hydraulic mast lift speed will be sluggish . TEST OPTIONS Verity repair. REASON FOR QUESTION If hydraulic mast speed is normal, fault has been corrected. 2-486