TM 10-3930-671-24 NOTE The instruction below applies to polished and machined steel parts not protected by cadmium, tin, copper, or other plating or surface treatment.  Bare metal must be free of moisture. f. Bare  steel  surfaces  should  be  protected  from  oxidation  while  awaiting  any  repair  step.    Dip  or  spray  parts  in corrosion preventive compound.  Aluminum parts may require protection in high salt atmospheres. g. Welding and brazing process may be used to repair cracks in external steel parts, such as brackets, panels, and light  framework.    These  processes  should  only  be  attempted  when  replacement  parts  are  not  available.    Welding  and brazing of castings and running parts or parts under great stress is not permissible, except in emergencies. h. Whenever installing studs, use a proper driver.  Before driving a stud, inspect hole for chips and liquid. Blow out any foreign matter. Start stud by hand.  If stud will not start into hole, it is too large or has a defective end thread.  Befo re final  insertion,  coat  thread  with  a  film  of  antiseize  compound.    Turn  stud  in  slowly  to  prevent  overheating  and  galling  of casting metal.  Drive stud to proper "setting height," which is the total projecting length.  While driving, observe required torque (Table 4-2).  This must be greater than nut tightening torque for same size bolt but not enough to damage casting as it approaches its correct engagement depth. i. Replace  all  broken,  worn,  burned,  or  pinched  electrical  wiring.    Wires  with  several  broken  strands  must  be replaced.  Broken strands increase the resistance of the wire and impair efficiency of the electrical components, especially the ignition system. j. Replace   all   loose   electrical   connections.      If   electrical   connection   is   protected   with   a   coating   of   silicone waterproofing during removal, apply a heavy coating of silicone during installation to electrical connection. k. Replace  all  broken,  frayed,  crimped,  or  soft  flexible  lines  and  hoses.    Replace  fittings  which  are  stripped  or damaged.  Replace entire flexible hose if fittings are damaged.  Make sure the hose clamps do  not  crimp  hoses.    With engine OFF, operate hydraulic controls to relieve all hydraulic pressure prior to working on hoses. I. Replace  any  bolt,  screw,  or  nut  with  damaged  threads.    Inspect  tapped  holes  for  thread  damage.    If  cross- threading is evident, re-tap the hole for next size screw or stud.  When re-tapping will result in weakening the part, or when the cost of the part makes re-tapping impractical, replace the damaged part. 3-7. GENERAL ASSEMBLY AND INSTALLATION INSTRUCTIONS. a. Remove protective grease coatings from new parts before installation. b. To replace an o-ring, first clean the groove, then stretch packing and place into position.  Rotate component on flat surface while applying a downward pressure to uniformly press the o-ring into position. c. To provide added sealing for gaskets, coat both sides with sealant.  Be sure that all traces of the previous gasket and sealant are removed before installing the new gasket. d. Install oil seals with seal lip facing in, applying an even force to the other edge of seal.  Coat oil seals evenly with oil or grease before installing.  If oil seals are to be installed over keyed or splined shafts, use a guide to prevent sharp edges of keyway or spline from cutting the leather or neoprene seal.  Make certain the guide edges are not sharp and are bent slightly inward so they do not cut the seal. e. When mounting bearings on shafts, always apply force to the inner bearing cups.  When mounting bearings into housing, apply the force to the outer bearing cup. 3-5