TM10-3930-660-34 4-3.  FUEL INJECTOR - TEST/REPLACE (Cont’d) CAUTION If rust has formed on injector hold-down nut, injector can turn in its bore as hold-down nut is loosened.  Dissolve and loosen rust as instructed in STEP 6.  Failure to follow instructions in STEP 6 can result in severe damage to cylinder head. 7.  IF NECESSARY,  APPLY RUST PENETRATING SOLVENT TO INJECTOR HOLD-DOWN NUT AND ALLOW SOLVENT TO REMAIN FOR A MINIMUM OF THREE MINUTES.  THEN TAP AGAINST INJECTOR BODY WITH HAMMER AND DRIFT PIN TO LOOSEN RUST. 8.  HOLD INJECTOR BODY WITH AN ADJUSTABLE WRENCH WHILE TURNING HOLD-DOWN NUT OUT OF INJECTOR BORE WITH A BOX END WRENCH. 9.  REMOVE INJECTOR (12).  REMOVE AND DISCARD COPPER INJECTOR SEAL (13). CLEANING RINSE NOZZLE WITH SOLVENT,  PARA. 2-10. INSPECTION INSPECT NEEDLE TIP FOR ROUGHNESS OR EROSION.  NOTE THAT ROUGH MACHINED APPEARANCE IS NORMAL FOR PRESSURE SHOULDER. TESTING 1.  OPENING PRESSURE TEST. WARNING Keep clear of test spray from nozzle.  Fluid at test pressures can penetrate skin, causing infection and possible death. 4-6