The next thing you'll need is a set of jeweler's screwdrivers, sometimes called "precision" screwdrivers. They're only a few dollars at the hardware store and you'll be surprised how often you use them on electronics, watches, etc.

This Timex Ironman watch has four tiny Phillips screws holding on the rear plate. Unfortunately my tiny Phillips screwdrivers did not fit so I used a Flathead screwdriver to remove the screws. With the rear plate removed, carefully remove the gasket that seals the plate and prevents moisture from getting inside the watch. If you watch is like mine, the battery is held against the watch mechanism with a small plastic and metal sleeve. This sleeve is released with a small clip and the battery slides out. Make sure to install the new battery in the same direction as the old one.
If the watch mechanism comes out, which happened to me, you need to make sure it is lined up properly when it is reinstalled. The buttons on the outside of the watch have small pistons that run through the watch housing and press against tiny spring clips on the watch mechanism in order to activate the different options on the watch. You need to make sure that the spring switches are lined up with the button pistons. If they aren't lined up properly then the buttons on the outside of the watch will not work. I had to reopen my watch several times before I figured out that the switches were not lined up properly.
When the new battery is in, reinstall the gasket into the grove on the back of the watch. Place the rear plate on the watch and reinstall the screws. Tweezers can help pick up the tiny screws and get them in the holes just don't squeeze too tightly or the screw will fly across the room and you'll never find it. Be careful replacing the gasket and the rear plate. If it's not lined up exactly right, your watch will no longer be waterproof.
If the watch mechanism comes out, which happened to me, you need to make sure it is lined up properly when it is reinstalled. The buttons on the outside of the watch have small pistons that run through the watch housing and press against tiny spring clips on the watch mechanism in order to activate the different options on the watch. You need to make sure that the spring switches are lined up with the button pistons. If they aren't lined up properly then the buttons on the outside of the watch will not work. I had to reopen my watch several times before I figured out that the switches were not lined up properly.When the new battery is in, reinstall the gasket into the grove on the back of the watch. Place the rear plate on the watch and reinstall the screws. Tweezers can help pick up the tiny screws and get them in the holes just don't squeeze too tightly or the screw will fly across the room and you'll never find it. Be careful replacing the gasket and the rear plate. If it's not lined up exactly right, your watch will no longer be waterproof.















