DAve Nelson I recognize this is an old question. This answer is just in case somebody still has this camera and wants to change the RTC battery. The battery part number is 1-756-710-12. It is located on the flex cable below the flash capacitor. Use this guide [guide|19401] to get to it. Step 7 in this guide shows the battery. To change the battery is not as complicated as it seems just follow that guide.