I unscrewed the back of my watch to replace the batteries, while doing so, a thin rubber gasket fell out. I am unsure where it goes. Does it go around the rim of the back of the case, or does it goes in the inside of the watch?

swiss army batt 20110106 1810

The rubber gasket is the waterproof seal, to get the proper one you need to go to Timex or an approved repairer!

The back of this watch doesn't pry off, it screws off.
I used the open tip of a needle-nose pliers to unscrew the back of the watch by inserting the the tips into opposing grooves in the back of the watch and turning it counter-clockwise.

Once the back of the watch is off, there are a few slotted screws that appear to hold a metal cover over the back of the watch 'guts', you'll need a jeweler's screwdriver to remove these screws (I counted 3 of them).

The battery is right under this cover.

When re-assembling the watch, I would apply a thin coat of sewing machine oil, or some other non-reactive lubricant, to the black gasket seal which should be on the back cover of the watch.

Yes. In your watch, as with most wristwatches that have a snap-fit case back, there's a thin neoprene gasket that sits either in a groove cast into the watch case or around the part of the case back that snaps into the watch case. Either way, the gasket is designed to further reduce the amount of moisture that can wick in between the tiny gap between the case back and the watch body.

As a matter of procedure, for maximum water resistance, this gasket is supposed to be changed every time the watch is opened (for example, when the battery is replaced). As a practical matter, however, I have often reused a gasket if it has not been distorted from pressure or mis-installation (lots of these gaskets end up crimped or pinched when they slip out of position as the case back is pressed into place). Does it provide reduced water resistance? Possibly, though moisture more often enters a watch fastest through the opening for the stem used to set the time. Leaving the back gasket out entirely, however, definitely creates an easy path for sweat and moisture to enter a watch.

Hi Susan, most Watches will require a tool to remove the back, some use a knife like tool, and some use an adjustable key type tool to fit the slots of the watch cover, so that you can unscrew the back off. Sometimes you can use a thin knife too, be very careful not to cut yourself, and also not to damage the rubber gasket. The gasket sometimes will need replacement on some watches if they are waterproof. I recommend having a watch expert look at it if you feel you can't do this yourself.
Also the tools are available on eBay. I hope this helps you. Joe

Spread the towel out on a flat surface.

Remove the watchband if necessary in order to access the back of the watch.

Unscrew the back protector from the watch using the correct size miniature screw driver. Place the screws in a small pile on the towel. Be careful not to drop them as they are difficult to find.

Remove the back plate by unscrewing the small screws. There is a tiny spring on the underneath of the back plate. It may be visible, or not. Make sure not to turn the watch upside down or the spring will dislodge.

Remove the rubber protector to find the battery.

Use sharp point tweezers to remove the clasp covering the battery. There is a small hole at one end of the clasp. Insert one end of the tweezers into the hole to spring the clasp loose.

Remove the old battery with tweezers.

Insert New Battery and Reassemble Watch

Pick up the new battery using regular tweezers and put it into place. Do not touch the battery with your fingers.

Replace the clasp over the top of the new battery.

Perform a reset by touching the AC contact with one part of the tweezers and the back of the battery with the other part. Hold for a few seconds. Lift the watch carefully and look up at the front to make sure the watch is working. Do not turn the watch over.

Replace the rubber cover.

Replace the back plate by screwing the small screws back into place.

Replace the back protector by screwing the small screws back into place.

Reattach the watch band to the watch face.

Feel a bit unnerved by this? Find a local jeweler. Best regards.
Jewel

Get the screwdriver and start to unscrew all the screws relating to band and rubber casing. Then undo springbars. Then unscrew caseback screws, take out the rubber gasket, unscrew the battery contact screws and take out the battery. Buy exactly the same one and replace it, then do all the operations in the same way other way round. Rate me, please.

It either sets into a small groove on the back of the watch or it simply goes on the back cover and seats against the back of the watch when you re-install the cover to form a gasket to water proof the watch

hi
i am not an expert in this particular case but i followed theses below steps . here are they.....

Unscrew the case back with a case back tool (aka Jaxa wrench) which engages
the notches in the case back. I'm assuming the watch has a screw back - if
it has notches it does. Pop out the old battery.

In some watches you have to
unscrew a clip but in most the battery pops right out. Examine movement for
evidence of battery leakage or other damage. Carefully clear away any crud
at the edge of the case - the tiniest metal shaving will short out the coil.
Install new battery of same type. Handle new battery with non-metal tweezers
or rubber gloves, never bare fingers. Inspect case back gasket or preferably
just replace it with new o-ring of same size. Gasket should be lubricated
with silicone grease. Reinstall case back using wrench. If you are
concerned with water resistance the watch needs to be tested in a pressure
test machine. I'm sure the pros have more tips but this should suffice for a
Timex where it would not be a big loss to damage or break the watch.

i hope you can successfully replace the battery
thank you

It really is best to have a professional install it, but if you would like to attempt to try it yourself, you will need certain tools. Take a small phillips-head screwdriver and remove the four screws on the back of the watch. Take off the back. Be careful not to mess up the seal (rubber round gasket). You will see a battery strap with three prongs with screws holding down your lithium battery. Unscrew any two of the three screws, and using a tweezer, pull out the battery. Put in the same number battery (probably 2016) making sure to insert it positive side up. Rescrew the screws. Next to one of the screws that you unscrewed, there will be another piece protruding off the battery strap, which almost hits the circuit board. Take your tweezers and lightly press it down to make contact and hold for 3 seconds. Replace your backing and screws.