This clock movement is called a "fit-up" because it is designed to "press-fit" into the DUBLIN or MADISON for easy "AA" battery installation and removal or for time-setting. To remove the "AA" battery, insert your thumbnail or other small object into the slot at the bottom of the battery case and pull away from the movement.
Note the diagram of a 1.5 volt "AA" battery on top of and inside the battery case for proper orientation of the "AA" battery. Adjust the time on the small, serrated time-set wheel above and to the left of the battery case. This may be rotated in either a clockwise or counterclockwise direction. It is recommended that the battery be changed annually.