TM 10-3930-671-24 f. Lubricate all preformed packings with a thin coat of hydraulic fluid before installation. g. Lubricate bearings before assembly with the lubricant normally used in the related housing or container.  This will provide lubrication during the first run-in until lubricant from the system can reach the bearings. h. Refer to identifying tags and sketches made at removal. i In general, after a hydraulic component has been removed, or lines have been broken, fill pump/motor and lines with hydraulic fluid upon installation. j. In  a  closed  loop  system,  whenever  a  pump/motor  has  been  diagnosed  as  faulty,  always  replace  corresponding pump/motor. k. Test operation after installation.  Inspect for leaks, vibration, noise, and misalignment.  Recheck after a week of operation. I. Always change filters after changing a hydraulic component, then again after 50 hours of operation. 3-8. PMCS INTRODUCTORY MATERIAL. This  section  contains  PMCS  instructions  for  the  truck.    The  PMCS  Table  contains  checks  and  services  necessary  to ensure that the truck is ready for operation.  Unit PMCS procedures are defined by the MAC. Unit PMCS is performed at the intervals specified in Table 4-1.  Operator Preventive Maintenance Checks and Services in TM 10-3930-671-10 should be completed before performing unit PMCS. 3-9. MAINTENANCE FORMS AND RECORDS. Maintenance forms and records provide permanent records of maintenance services, repairs, and modifications made on the truck.  They provide reports to organizational maintenance and the commander, and they serve as a checklist to find out what was wrong with the truck after its last use and whether those faults have been fixed.  For information needed on forms and records, see DA Pam 738-750. 3-10. GENERAL PMCS PROCEDURES AND CONDITIONS. The following paragraph describes general procedures and conditions that should be observed when performing PMCS. a. General Guidelines. (1) Limit repairs to those actions necessary to ensure mission reliability, safety of personnel, and prevention of further damage or deterioration.  Repairs, replacements, or services for cosmetic purposes are forbidden. (2) Lube oil sampling.  Engine and transmission oils must be sampled at 50 hours of operation or 90 days, whichever occurs first, for Active Army Units.  Reserve and National Guard Activities will use 50 hours or 180 days, whichever occurs first, as the prescribed interval.  Hydraulic fluid will be sampled once-a-year. Sampling will be performed as prescribed by DA Pam 738-750. (3) Lube   oil   filters.      Oil   filters   shall   be   serviced/cleaned/changed   as   applicable   when   they   are   known   to   be contaminated or clogged, service is recommended by AOAP laboratory analysis, or at prescribed hard-time intervals. 3-6