This guy is very highly regarded by us vintage watch lunatics. Very reasonable prices to boot.
Link
Breitling now has no link to the older incarnation of the company. It's another company that bought the name when Breitling went out of business back in the late 70s/early 80s. I'm not sure if they support older models in the same way that Omega or Rolex do. However, I don't think it will be too problematic finding a chronograph pusher for it.