Thanks to Amazon Sunday delivery, I was able to rebuild the petcock today.
I followed this guide:
http://faq.ninja250.org/wiki/Rebuild...tcock/fuel_tap
I used a shmear of Vaseline on the O-ring, to facilitate rotating between On, Off, and Reserve.
I decided to hold off on the separate diaphragm, and I think that I lucked out, as mine looks great. We'll see. once I reassemble, and fire up the bike.