_d. Testing for leaks in pressure system._ After charging, and as few hours as possible before a mission, use an 0-3,000-pound gage furnished in service kit to test pressure. (Fig 32) To install gage, unscrew check-valve cap and screw gage in check-valve body. If pressure has fallen below that to which the tank was charged (Par 32), a leak is indicated. Remove gage, replace check-valve cap, and check for leaks at joints between pressure tank and valve and between tank valve and check valve. (A wrench should be used to tighten cap on check-valve body so as to avoid producing an additional leak.) Large leaks can be felt or heard. Small leaks can be detected by coating joints with soap-and-water solution. Bubbles indicate leaks. If a leak is revealed between pressure tank and pressure-tank valve, or between check valve and pressure-tank valve, replace all three as a unit. If tests do not show up the leak the tank may have been improperly charged. It should be recharged and then retested. 54. SERVICE WHEN FIRING. _a. Failure to ignite._ Pull trigger repeatedly. If ignition cylinder still fails to ignite, dirt may be wedged in ignition head. Unscrew shield one-half turn. Screw it back, rapping shield with the hand while turning. This should dislodge foreign matter. Pull trigger again. Repeat procedure, if necessary. _b. Safety head “blows” (breaks)._ If safety head breaks, firing mission cannot be carried out. On return, have head replaced. (Par 69) Follow test procedure. (Par 56 _b_) 55. SERVICE AFTER FIRING. _a. Unloading._ Remove ignition cylinder (Par 30), close pressure-tank valve, and blow out remaining fuel and pressure. (Par 30) _b. Removal of equipment._ Release the body straps, then the shoulder straps. If prone, lie on side and allow tank group to roll off onto ground. If standing or kneeling, take care that tank group does not drop on feet or legs. _c. Correcting or reporting._ Correct any failures or difficulties or report them as soon as possible to service or maintenance personnel. _d. Gun._ Remove shield (Par 18) and clean interior of shield with cloth. Clean holes in shield with wire or wooden splint. Clean external surfaces of barrel, nozzle, needle, and other parts. Check cleanliness and adjustment of needle. (Par 75 _d_) Check trigger for operation. Lubricate. (Par 49) _e. Fuel tanks and passages._ Remove plugs (Par 69 _b_). Drain any remaining fuel. Use gasoline to remove residues of thickened fuels before they have a chance to harden and obstruct passages. If necessary, fill tanks with gasoline and allow to stand for several hours, shaking occasionally. Drain and repeat if necessary. _f. Safety head._ Check head to see if it is ruptured; if it is, replace. (Par 69) Follow test procedure. (Par 56 _b_) _g. Pressure-tank valve._ If weapon is to be stored, open pressure-tank valve and leave it open until next charging. _h. Carrier._ Scrub, if necessary, with soap and water, or gasoline.