Agie Mondo Star crashed out of blue

My Mondo 20 Futura V EDM just crushed a workpiece and I can find no reason for it.
It crushed a part with impressive force after running fine for the day.
The error code E42 indicates "axis obstruction" (may mean the part was in the way of where it wanted to go).
The Z position displayed was a negative number below its program values.
The machine seems to work now but I need to know why or at least learn what methods are used to govern the servo.
Does anyone have any ideas?

I bought this new around 2002, it gets light use and had sat for months until today when I greased it up and starting running some small parts.

the mondo series sinkers use dc motors with rotary encoders to move the axes. The Pacer\Fine Interpolator
boards handle the math that dictates how the motor/encoder moves. I have serviced these machines for years
and what you are describing can only occur if the encoder or Pacer/Fine interpolator is defective. If that
is the case, it will happen again and more frequently. How is your incoming power? Stable?

Hi jdd.
The power is generally good here and there were no flickers at the time.
I have some more details and an interesting test.
The machine wasn't back to normal, it moves fine but when an erosion starts it throws an alarm.
Just before that E5 alarm, it moves about .008" but in the opposite direction and outside of the starting point value.

The alarm description from the manual:
"The generator is not ready, resistor box is overheating, generator transistor failure or could not complete it's self tests."

Cause: "Bad generator communications SBC-02 malfunction"

Action to take: "check fiber optic cables, re-seat SBC-02 board"

Those fiber optic cables have always been a problem. Some days an axis will not move after powering up and I have to re-seat cables which does it. Aside from re-seating the hell out of stuff, with no change, I did a test.
I changed the axis in the 'programmed' erosion from Z to X.
It behaved the exact same way, same movement just before the alarm but now in the X axis.

I'm going out to swap some fiber cables...

The E5 alarm is caused by one of two issues: 1) Bad generator board. The GPM-50 board is in the lower rack of
boards to the left of the SBC-02 board. This board should have three large LED's lit when the machine is at idle
and not in erosion. If there are four lights lit, then the GPM-50 (generator board) is bad. If there is a small
led lit on the GPM-50 then that signifies which transistor is bad.

2) You have a bad fan switch in the resistor box. The resistor box is in the back of the control unit and there
is a paddle switch to make sure the fans are operating to cool the resitors.

Thank you jdd. You got it.
Agie support was helpful, it's running again after disconnecting that fan switch. I don't think this had anything to do with the crash but was from me cleaning the resistor box after.

I added jumper leads from the ram and table that clip onto setups. Also cleaned the C axis brushes.
My best guess that loss of continuity is the cause and the lack of crash protection such as current sensing the drive motors made it a disaster.