The Timex Expedition series of watches offers the user options for altimeters, compasses and timepieces. The Expedition series use CR 2016 cell batteries. Over time and use, the battery wears out, requiring a fresh one to be placed in the watch. Instead of taking the watch to a jeweller, save time and money and replace it yourself. The process is a shade tricky, as the screws on the watch are very small, requiring a specialised optician's screwdriver to take the housing plate off.
Turn the Timex Expedition upside down and place it on a flat, level surface.
Insert the screwdriver into the four tiny screws around the watch housing plate and turn them counterclockwise to remove them. Use the magnifying glass to find the screw heads if needed.
Pry the housing plate up off the watch. Turn the Expedition over to allow the battery to fall out of the housing. Turn it back over again and set it down on the bench.
Place the new battery in the housing and put the plate back onto the watch. Insert the four screws back into the plate and screw them clockwise to secure the plate back to the watch.
Follow the Expedition setting guide to reset the time and altitude and calibrate the compass with the new battery.