Okay, I reheated the two middle joints and retested without the 6080. New measurements are:
OA: 50V
OB: 70V
1A: 249V
1B: 249V
I noticed that right after powering on, OA gives a reading of around 70V but it quickly drops to 48-50V within around 15 seconds. I tried replacing my 12AU7 tube but that made no difference in the reading.