Aviator watches were developed almost simultaneously with the aeroplane. Early pilots needed a tough and accurate time piece to keep track of their flight time from one time zone to another. As planes went into more inhospitable areas, aviator watches added functions such as magnetic shielding. Originally, aviator watches were only issued by military personnel, but as pilots came home after WWII, aviator watches entered the civilian market. Seiko was one of many watch companies which carried lines of aviator and pilot watches that boasted a variety of functions and impeccable accuracy. Seiko discontinued aviator watches in 1999.
Find the brackets that hold the watch band to the watch. There is a tiny bar, called a spring bar, that holds the watch band in place.
Slide the spring bar tool, a thin piece of metal, into the side of the watch band bracket. Compress the spring bar with the tool and the watch band will pop out of the bracket.
Slip the spring bar into the holes in the new watchband. Slide one end of the spring bar into the lug of the bracket. Compress the spring bar and slide it behind the lug on the other side of the bracket. Carefully pull the spring bar forward until it slides into the lug, securing the watch band.
Measure the watch around the wrist. Estimate the number of links to be removed.
Find the removable links closest to the clasp. They should be either the first or second link from the clasp. There are small pins holding the links together. The ends of the pins will be visible on both sides with one end slightly larger than the other.
Push the smaller end with the point of the jewellers awl. The wider end will emerge from the watch band. Using the tweezers, fully remove the pin.
Remove links from both sides of the clasp. This keeps the clasp centred on the wrist.
Re-attach the centre clasp to the shortened watch band. Line up the links and carefully insert the pin from the wider hole. Gently push the pin until both ends are flush with the watch band.
Place the watch face down on a soft surface.
Find the opening groove on the back. This will be a small indentation between the watch case and the back.
Insert the spring bar tool and pry the back off the case. Find the battery.
Take the battery to a jewellery or electronics store. They will test the battery and sell you the proper replacement. Replace the new battery.
Line up the back of watch with the case. Gently snap the pieces back together.
Do not remove the back of a pressurised watch. This will break the seal and may void the warranty. Instead take the watch for professional care. Do not be tempted to "clean" the inside of a watch. Even the softest cloths will leave lint and other debris inside the watch and may affect performance. If you spot dirt or debris in the watch, it means that the watch's seals are bad. Close the back and immediately take to the watch to a professional.