Watch pins hold the links of a watch bracelet together. Three to four links on each side of the clasp can be removed so the owner can resize the bracelet. The most common type of watch pin is pushed into the link, but the type of link that can become loose during wear is a screw pin, which is screwed into the link. Screw pins are found on high-end luxury watches, such as Rolex.
Look for a tiny screws on the edge of the links. The screws will be on the links nearest to the clasp. Turn your watch on its side so that the links are vertical and the edges of the links with the screws are facing up.
Place the tip of your tiny screwdriver on a screw pin that is loose. Turn the screwdriver counter-clockwise to remove the pin.
Use a pair of pliers or tweezers to completely remove the pin from the link once the pin is unscrewed.
Roll the threads of the screw pin in an adhesive glue that can be used on metal. The glue should not get on the pin shaft, because it will make the bracelet stiff.
Insert the tip of a toothpick into the glue, then place the glue in the bottom of the link where the pin screws into the link.
Insert the pin back into its link. Be careful not to get the glue on any other part of the watch. Carefully screw the pin into the link by turning your screwdriver clockwise until the screw stops.
Repeat Steps 2 through 6 on any other loose links on your bracelet.
You can find a small screwdriver in a jeweller's kit that comes with a range of small screwdrivers made to work on watches and jewellery.