Beyond these basic steps, watch maintenance should be performed only by qualified professionals. Have your watches cleaned and lubricated every two to three years. Watches are easy to store and maintain, and raise only a few issues of upkeep. Moisture can get into a watch through gaps in the case or through a break in the crystal. If this happens, it can rust metal parts and severely damage the movement.
Magnetism can ruin a mechanical watch.
If some of the metal parts within your watch's movement become magnetized, it will disrupt their accuracy, perhaps irreversibly. Unless you have been properly trained, there is little you can do to repair your watch beyond searching for a trustworthy repair person. If you cannot send the watch back to the original manufacturer, ask reputable dealers or other vendors to suggest watch repair operations that they either use or recommend. If that unfortunate moment arrives when you must take your watch to be fixed, ask for a written estimate of both cost and time of repair in advance.