Mission Berlin 05 – Haven't We Met Before?

When the music box is opened up, it appears it is more than broken. Paul Winkler finds a piece of paper inside with the numbers 19610813 written on it. What do they mean? And what is Paul Winkler talking about? Anna asks him if he can repair the clock and he says that they know each other. In this bewildered state, Anna does her back up save and has 90 minutes and two lives left. She has followed the music as the phrase suggested but what does "division is the solution" mean?