two dead 4000/90 exhibiting same symptom, power supply question

[Tobias Nygren <tnn-netbsd%nygren.pp.se@localhost>]

Hi VAX aficionados,

Pulled two VS4000/90 out of storage today, where they have been
sitting for at least 7 years. Both no longer working. I'm pretty
sure at least one of them used to work.

S3 switch is up. when I apply power, all 8 LEDs stay permantently lit.
Reseated all components and pulled out the power supplies for
measurements:

LABEL  |   PSU1 |   PSU2
-------+--------+-------
 +5.1V |  +5.2V |  +5.1V
+12.1V | +11.8V | +11.8V 
 +3.3V |  +3.3V |  +3.3V
  -12V |   -12V |   -12V 
   -9V |  -6.0V |  -5.8V

+11.8V on +12.1V sounds acceptable but the -9V is way off spec.
Does anyone know how it should measure without a load applied
and if this reference is critical for operation?

Kind regards,
-Tobias