I change them myself also. One thing to note that on some timex and casio's, it is necessary to short out the plus side of the battery with a contact (usually labelled AC) once the battery is changed. Sometimes it works ok without being shorted but not always. I use a pin on the contact and tweezers from a victorinox knife to complete the short and it works well. There is usually a label on the battery holder with an arrow towards the AC contact.Most dead watches I find work well once again once a new battery is installed. It seems that most people won't change them or get them changed once a watch dies.John.