TM10-3930-660-34 (2) Only minor repairs to machined surfaces, flanges and gasket mating surfaces are permitted.  Remove minor nicks, burrs and 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 castings. (4) Repair damaged threaded pipe plug or screw threads with a tap.  Repair oversize holes with threaded inserts. c.  Bearings.  Refer to TM9-214 for repair of bearings. d.  Studs.  Replace all bent and stretched studs.  Repair minor thread damage with a thread die.  Replace studs having stripped or damaged threads as outlined below: (1) Remove using a stud remover.  Back studs out slowly to avoid heat buildup and seizure that can cause stud to break off. (2) If studs break off too short to use a stud remover, use a stud extractor to remove or use a "welding method". CAUTION Refer to TM9-237, Welding Instructions, to avoid damage to castings if welding method is used. (3) Broken studs can be removed by welding bar stock or a nut to stud and removing with wrench. (4) Install replacement stud slowly to prevent heat buildup and snapping off. e.  Gears. (1) Remove gears using pullers. (2) Only minor repairs to gears are permitted.  Remove minor nicks, burrs or scratches on gear teeth with: (a) Fine mill file. (b) Crocus cloth dipped in cleaning solvent. (3) If keyways are worn or enlarged, replace gear. f.  Bushings and Bushing Type Bearings.  When bushings and bushing type bearings seize to a shaft and spin in the bore, the associated part must also be replaced. 2-23