My understanding is that once a movement is 30+ years out of production, Rolex USA won't service it anymore. I've heard that Rolex service centers in other countries will repair some of the very old calibers if they have the parts. It's been rumored that Rolex Cuba is sitting on a treasure trove of 1950's parts, just waiting for the embargo between the USA and Cuba to be lifted. But that's just a rumor.
Not only that, Rolex will sometimes refuse to service watches unless you agree to all the replacement parts. And of course, they refuse to return any original parts replaced.
Take care,
gatorcpa