[Illustration: Fig 54. Valve-needle adjustment. Solid lines show needle in correct open position with point at smallest diameter of nozzle. Broken lines show needle in closed position.] (1) _Damaged parts._ Replace worn or damaged parts. If the diaphragm shows evidence of tears or separation, or if leaks occur at the diaphragm, replace the valve-diaphragm assembly. (2) _Valve spring._ If valve spring has lost resiliency, grasp it by the ends and stretch slightly, or replace. (3) _Nozzle leaks._ If valve leaks at nozzle, and cleaning (Par 55 _d_) does not remedy the leak, adjust needle (see _d_ above). If leak persists, either replace barrel and needle, or lap seat. To lap, place lapping compound on seat (in nozzle) and on needle point. Turn needle in seat until parts make a tight connection when seated. Remove lapping compound, reassemble, adjust needle, and test fire. (4) _Atomizer hole._ If atomizer hole is clogged, clean with fine wire. (Par 52 _i_) 76. IGNITION HEAD. _a. Description and functioning._ (Fig 55) The ignition head ignites the fuel when the flame thrower is fired. It is mounted on the fore part of the barrel. It consists of: (1) _Ignition-head body_, which includes half of the front grip. Three set screws serve to tighten the ignition-head body to the barrel. The ignition-head body is made of aluminum. (2) _Trigger and trigger bearing_, held between the ignition-head body and the coverplate by the trigger screw. (3) _Trigger rod_, one end of which is held in the trigger bearing, the other extending through the ignition-head body. Pulling the trigger shoves the trigger rod forward, causing it to push a match in the ignition cylinder. The match ignites an incendiary charge in the ignition cylinder. (4) _Trigger spring_, which hooks over a projection of the trigger and is held at its lower end by a screw, which is held in the ignition-head body. This spring pulls the trigger rod back from the firing position after the firer releases the trigger. (5) _Latch_, located in the ignition-head body, in front of and above the trigger guard. The latch, set on a pin, engages the notch of the ignition shield, locking it in place. A latch spring holds latch in position. (6) _Coverplate_, an aluminum casting which constitutes the left section of the front grip and covers the working parts seated in the ignition head body. The coverplate and body are held together by four screws and four lock washers. (7) _Spring case_, which turns the ignition cylinder when the trigger is pulled. (_a_) Four projections on the inner spring case are bent over the outer spring case to hold the two parts together.