Thanks for starting this discussion.
Here are the values you were asking about.
When everything is connected, what voltages do you see:
At 15V TP. 1.675vdc
At the emitter of Q1546. 1.683vdc
At the base of Q1546. 2.223vdc
pin 7 of U1524B 2.988vdc
base of Q1548B. 2.084vdc
Voltage across R1549 (this tells us how much current is pulled from Q1546). 0.008vdc
We are looking for a possible high current out of U1524B pin 7 (~ 10mA).