TM 9-2815-225-34&P 3-9. REPAIR (Contd) CAUTION Repaired items must be thoroughly cleaned to remove metal chips and abrasives to prevent them from entering working parts of engine.  Refer to Cleaning, para. 3-6. b.    Castings. (1)    All cracked castings will be replaced. (2)    Only minor repairs to machined surfaces, flanges, and gasket mating surfaces are permitted.  Remove minor nicks, burrs, and/or scratches with: (a)    Fine mill file. (b)    Crocus cloth dipped in cleaning solvent. (c)    Lapping across a surface plate. (3)    Remachining of machined surfaces to repair damage, warpage, or uneven surfaces is not permitted.  Replace casting. (4)    Repair damaged pipe threads and machine threads in castings with the proper thread tap.  Repair oversize holes with threaded inserts. c.    Ball-Roller Bearings.  See TM 9-214. d.    Studs.    Replace  all  bent  or  stretched  studs.    Repair  minor  thread  damage  with  a  thread  chaser.    Replace  studs  having stripped or damaged threads as outlined below: (1)    Using a stud remover, remove stud.  Back stud out slowly to avoid heat buildup and seizure, which can cause stud to break off. CAUTION See TM 9-237 (Welding Instructions) to avoid damage to castings if welding method is used. (2)    If studs break off too short to use a stud remover, use an extractor or the "welding method." (3)    Broken studs can be removed by welding bar stock or a nut to stud and removing with wrench. NOTE Standard studs may have a coarse thread on one end and a fine thread on the other end. The coarse threaded end is usually installed on the casting.  Studs having coarse threads at both  ends  are  used  in  some  applications.    The  shorter  threaded  end  is  intended  to  be installed on the casting.  See Appendix B for correct part number. (4)    All  replacement  studs  have  a  special  coating  and  must  have  a  small  amount  of  antiseize  compound  (MIL-A-13881) applied to their threads before installing.  Install replacement stud slowly to prevent heat buildup and snapping off. e.    Gears. (1)    Remove gears using suitable pullers. (2)    Use the same methods described in para. 3-9.b., step 2, to remove minor nicks, burrs, or scratches from gear teeth. (3)    If keyways are worn or enlarged, replace gear. f.    Bushings and Bushing-Type Bearings.  When bushings and bushing-type bearings become seized to a shaft or spin in a bore, they must be replaced along with their associated parts. g.    Oil Seals. (1)    Remove oil seals by pressing or prying out, being careful not to damage casting or adapter bore. (2)    Always install new oil seals using proper seal driver tool. 3-6