Are you 100% sure both halves of the 12AU7 are glowing?
The 0V at A3 means that you either have half a dead 12AU7 (they very, very rarely just suddenly die on one side), or you have a bad solder joint that isn't allowing half of the 12AU7 to draw appropriate current. Perhaps posting some photos of the build around your 9 pin socket would be helpful.
-PB