If the base of the inflator QD fitting is leaking, use the 1/2" hex to remove the fitting and replace the o-ring. However, look closely if you see a leak. Sometimes the leak is not coming from the base of the fitting, but rather from the connection to the hose. There is a small o-ring in the female end of the hose fitting that is more frequently the source of the leak.
If the inflator is dribbling gas into the BC, we recommend replacing the entire assembly. However, if you wish to overhaul the inflator start by mating the spanner tangs to the two slots of the inlet valve cartridge assembly, then unscrew counter clockwise until the entire assembly can be removed.
Now disassemble the cartridge assembly. Depending on the design of the assembly, wse either a flat blade screw driver or the hex to keep the end of the spool from turning while you unscrew the plastic button. Once the button separates from the spool, push the spool out from cartridge barrel. Remove all the o-rings (noting their relative positions and sizes) and clean everything, including the inside of the barrel and the plastic body of the inflator, by briefly soaking in a 50/50 solution of white vinegar and water. If need be, scrub with a light application of a toothbrush but don't use an ultrasonic cleaner.
Replace the o-rings and reassemble. The o-rings must be clean and need not be lubricated. Some people lubricate the small 006 o-rings to provide a smoother operating feel, but we observe they are not lubricated at the factory in new inflators. (We do not lubricate because we think it attracts dirt and just gums up the works so that it has to be more frequently cleaned.) Tighten until snug, but do not over tighten or you will crack the plastic body. If the inflator still leaks or begins to leak within a few dives, then the surfaces which the o-rings seal against are worn and the entire inflator assembly should be replaced.
The manual exhaust is not pressurized and operates independently of the power inflation mechanism. The manual exhaust contains an additional O-ring that we've never seen fail. We don't recommend disassembling the manual exhaust assembly, and so we don't include the manual exhaust O-ring in our kit.