Unfortunately this is the problem with quartz movements, and especially older ones - technology moves on and so original parts become unavailable. (Mechanical watches are different as the technology hasn't really changed in a couple of hundred years and parts can always be fabricated if needs be).
Anyway, slight off the point there - your best bet will be to scour eBay and the like to find a donor Pluton, or even a watch by a different brand that happened to use the same base movement, as the movement in the Pluton wasn't Breitling-made. I'm not that familiar with the older quartz movements, but member "Sonyman" here certainly is, so may be worth dropping him a PM to see if he can tell you any other watches that used the same movement.
Once you have a donor watch, any competent watchmaker should be able to use the parts to repair yours, or more likely they will simply replace the entire movement with the donor's.
Obviously it's worth remembering that any donor watch will also be quite old as well, so any fix you do now will only likely have a finite lifespan. I know your watch obviously has sentimental value to you, but if you can overcome that it may be worth considering Breitling's offer of a discount on a new model......
Hope you get it sorted out.
since I don't recall doing it before!
