Point B has 0v when it should have 83v.
Tracing the circuit back, the voltage at B is going to be coming from V2 pins 2 & 7 (grid) and pins 8 & 3 (cathode).
Tracing it back further, the anodes on V2 (pins 1 & 6) go back to the 100k resistors (18 & 19). Which are connected to... Hang on a minute...
Completely missed that connection on the blue dashed wire (running under the board).
Time for an ugly jumper.