Digitech Hot Head distortion dropping voltage in 4 places (schematic included!)

[hc803]

No signal or LED light on this pedal right now.
I've checked my 9V battery across this entire pedal and I'm getting four places where it's not at least 9.37V:
D3 - 8.57V
D6 - 8.52V
R25 - 8.54V
R31 - 8.57V

I'm not great with schematics, but I got the original one from Digitech, the link is below.  Any ideas why the voltage is dropping and ideas on how to fix?  Thanks!

https://drive.google.com/file/d/0BwtSQmLG6D2GeU9ndExzbEl2SEU/view?usp=sharing

[Fender3D]

Why should you get 9.37V on those points?

D3 is a 6.2V zener, then it's strange you ain't got 6.2V there
D6 is after 1M resistor
R25 is after an inverter
R31 is there just for the LED, then it should be ok until it's supplied over ~4V

[hc803]

Hmm, ok.  I'm trying to figure out circuitry by doing this project, do you have any suggestions on what else to check?  Seems like the board is completing the circuit as far as power goes(?) but I can't figure why I'm not getting a signal or LED lighting.  Sorry for the newbie approach.

[Fender3D]

It may be almost anything... (although I swapped a lot of 4007s in DOD and Digitech pedals)

First:
http://www.diystompboxes.com/smfforum/index.php?topic=29816.0

Second:
try with a signal probe and check where signal disappears.