I would not recommend spectral sensitization of the Azo emulsion. I merely mentioned it and demonstrated that it can be done. If you want to do it, it should be added just before you add the spreading agent and the hardener. You hold for 15" before adding the spreading agent and the hardener and coat immediately. Depending on conditions, this addition speeds hardening up of the gelatin and you can end up with a ball of red jelly.
Did you solve the other problem?