[Elecraft] KPA 100 Power Supply Problem

[Vincent Denecker]

I have built K2 # 5236, including SSB, 160m, NB and DSP without any
problems but I now need help with the KPA 100. 
 
Initial receiver tests, SWR bridge null adjustment and power calibration
at 5 watts were ok on all bands.
 
The problem I have now is that when I turn on the high current power
supply, its voltage drops from 13.8 V to less than a volt (presumably as
a result of the PS protective circuit). I tried another high current
power supply, with the same result.
 
I  have done a thourough a visual inspection of the board but can't find
anything wrong. 
 
However using the low current  power supply, D13 cathode voltage seems
possibly too high (162 V) an U4 pin 8 voltage too low (-29V). 
Q1 and Q2 base resistance perhaps a bit too low ? (11.3 ohms)
 
What should I check next? Thanks in advance. 
 
73, Vincent G0LMX