Schaffner NSG2050 - Low output drive capability

[AndersJ]

The output voltage is half of what is expected, when the output is open circuit.
With a small load the output voltage falls dramatically.
The waveform looks good, timing wise.

The instrument has a 10 uF 10KV floating capacitor that is connected to the
output at the time of the surge. Connection is made with contactors
that can both positive and negative output polarity.

Both output polarities, and both output connectors have the same problem.

My hypothesis is that the negative side of the capacitor is not being grounded
when the pulse is generated, thus causing weakly driven outputs.
The only place I have seen, where this grounding might take place,
is on the impossible to reach circuit board at the rear end of the instrument.

Does anyone have a service manual?

All suggestions are more than welcome.
Anders J