Here's a pretty complete rebuild of that movement that the guy documented really well. This shows the microrotor which you can see once he removes the chrono. Pretty cool!The cal. 11/12 "Chronomatics" are automatic chrono movements, developed by a partnership of Heuer, Breitling, Hamilton/Buren and Dubois Depraz. It was one of the initial forays to develop an automatic chrono movement, introduced in 1969, marrying a Dubois Depraz chrono module with a purpose-built Buren derived microrotor movement. You just can't see the microrotor as it's under the chrono module.
Do some Googling and you should be able to find an exploded diagram that makes the construction clearer.