Ok .. I was confused when you said the band closest to the motor. That would be the 2nd gear band.
Bummer to see your rear band broke. I knew something would be broke in there. The rear band (or front for that matter) apply / anchoring systems typically don't just "fall out."
Hate to make light of the situation, but at least you'll learn how to rebuild the 904 / 727 now.
Good luck! Feel free to post up questions here, or e-mail me if you have any questions!