_c. Tank coupling._ Examine coupling for cleanliness and ease of movement of lock and cams. (Par 70) Clean if necessary. If washer is broken, replace, using screw driver to pry out. _d. Plugs._ Check filling plug and safety-head plug for completeness of parts (Par 69 _a_) and cleanliness of threads and seats. Clean, if necessary, with cloth. If rod or rod and chain have broken off and fallen in tank, turn tank upside down and remove. Remove deflector tube from head (using hand, not wrench). Inspect to see if diaphragm is intact. If diaphragm is ruptured, replace the safety head with an unbroken head. (Par 69 b, c) Reassemble plug, head, and deflector tube in left fuel tank. (Fig 11) Tube should face to rear and at a 45-degree angle to operator’s left shoulder. (Fig 18) Screw in deflector tube by hand; do not use wrench on deflector tube. Tighten lock nut with wrench. _e. Pressure-tank clamp._ The clamp should hold the pressure tank tightly in place. If tank is loose, a wooden splint or wedge under the clamp may be used as a temporary expedient. _f. Carrier-frame bolts._ Check tightness. Use wrench. _g. Carrier._ (Par 71) Examine all canvas, webbing, and cord for signs of mildew, rot, or wear. Replace defective parts. Move flame thrower to dryer storage if mildew occurs. _h. Cord (lashing)._ Check for tightness. If necessary, make tighter and use secure, slip-proof knots. When the tank group is filled with fuel and adjusted on the firer, its weight should be carried chiefly by the canvas and webbing, not by the metal frame. _i. Shoulder and body straps._ Adjust straps to fit firer. (Pars 19 and 71) A loose tank group can cause discomfort or injury when the wearer changes positions while on a mission. Check presence and condition of the two pins and two cotter pins which hold shoulder straps to steel support. Check fasteners. 52. BEFORE-OPERATION SERVICE OF GUN GROUP. The following services are to be performed before filling, charging, and loading with pressure, fuel, and ignition cylinder: _a. Hose nipple, tank end._ Examine to be sure nipple is clean and not badly nicked. If badly nicked, the nipple may not make a tight seal at the tank coupling. A leak and loss of pressure may result. See Paragraph 73 _d_ for repair of the nipple. _b. Fuel hose._ Examine surface of hose for cracks or other signs of deterioration. Special attention should be paid to portions adjacent to the gun and tank coupling, which are subjected to severe flexing. If hose is defective, replace. (Par 73 _b_, _c_) Do not patch. _c. Hose nipple, gun end._ Check tightness of threaded connection between hose and fuel-valve body, using hand or very light wrench pressure. _d. Shield._ Remove ignition shield. Check cleanliness of threads on shield and on ignition-head body. If not clean, use cloth. When reassembling (Par 18 _c_), shield should turn freely until it locks in correct position. _e. Valve lever and needle._