TM 10-3930-669-20 2.  TILT CYLINDERS DO NOT OPERATE OR OPERATE SLOWLY (CONT). KNOWN INFO Lift, shift.  and pivot cylinders operate. Tilt cylinder pin(s) OK. Hoses to tilt cylinders OK. Tilt control cable OK. POSSIBLE PROBLEMS Stack valve faulty. Tilt cylinder faulty. Mast tilt faulty. TEST OPTIONS Pressure test. STE/ICE-R #51. REASON FOR QUESTION If stack valve is faulty, tilt cylinder will not operate. 2-432