_c. Fuel valve._ Discharge all pressure from the gun by operating the fuel valve. Carefully remove the valve grip and grip support. (Par 74) Look for signs of leakage at the valve diaphragm. If a leak is present, replace valve-diaphragm assembly. (Pars 75 _b_ and 75 _c_) _d. Valve grip._ Disassemble the valve grip (Par 74) and lubricate. (Par 49) _e. Carrier._ Tighten the carrier cord. _f. Gun interior._ If thickened fuel has been fired, disassemble the gun. All parts should be cleaned of accumulations of dried fuel. Lubricate (Par 49) and reassemble. If liquid fuel has been fired, flush gun with clean gasoline. Disassemble only enough to lubricate. Reassemble. Section XV TROUBLE SHOOTING 57. PRECAUTIONS. First, remove the ignition cylinder. Then, before disassembling, servicing, or repairing parts which may be under pressure, be sure to release the pressure. Remove fuel, when necessary. 58. FUEL LEAKS. _Trouble_ _Remedy_ _a._ Defective or damaged If leak is observed in valve grip, valve-diaphragm assembly. disassemble. (Par 74) If diaphragm is torn, or damaged in any other way, remove and replace. (Par 75) _b._ Defective threaded Disconnect, using wrenches. If connections on fuel lines. thread is stripped or badly damaged, replace the threaded part. If threads appear to be sound, clean them and reconnect. If leak is between tank coupling and tank connector or between hose and fuel-valve body, apply anti-seize compound before rescrewing. Tighten joint with wrenches. _c._ Dirt or foreign matter Clean parts carefully with cloth before on seats or threads. reassembling. _d._ Leak at nozzle. Adjust needle. (Par 75 _d_) If leak persists, either replace needle and barrel as a unit or use lapping compound on parts. Turn needle in seat until parts make a tight connection when seated. Remove lapping compound and reassemble. _e._ Worn body of hose. Replace fuel-hose assembly. (Par 73) _f._ Leak at tank coupling. Remove and replace coupling washer if damaged. (Par 70) If hose nipple, tank end, is damaged, repair nipple (Par 73 _d_) or replace fuel-hose assembly. 59. SAFETY HEAD “BLOWS” (BREAKS).