- Sharp Knife
- Small Screwdriver (from an eyeglass kit)
- Tweezers (the sharper the better)
The first thing to do is check the back of the watch. If there are six notches in the back evenly spaced, you will need a needle nose pliers as well. These backs unscrew rather than pry off like most watch backs. They may be tight, so if it becomes too much of a struggle, go to a watchmaker.
The other backs need a knife to pry off. Usually there is a "lip" that the knife can fit underneath. Don't be afraid to be a little more aggressive with that sort of back. Be careful that you do not scratch anything.
Once the back is off, you should be able to locate this little round disk. Guess what that might be. If there is metal piece holding it in place, that is called a cell strap. Those need to be removed in order to get to the battery. Take the small screwdriver and CAREFULLY unscrew the cell strap screws. Use the tweezers to move the cell strap aside. At this point, the battery should be completely exposed. Using the tweezers, take it out. You can use a little more force than you think. However, beware of using too much.
On the battery will be some numbers. Go to a pharmacy or watch repair shop and match them up. Put the new one in, close it up and you are done. If the watch still does not run well or at all, you will have to have the watch fixed.
Once the battery is replaced, set it to the appropriate time.