Quoted from rvermeire:
How can this be measured (ohm/V ?) and what should be the outcome of the test ? (test in off or on mode?)
with the machine turned on, using a multi meter set on DC volts, put the black lead probe to any ground, there is one on the solenoid driver board marked GND, but the ground plane or braid will do, and the red lead probe to the loop tag marked TP2.
This TP2 may be under a plastic shield, warning of the high voltage present depending on whether yours is there.
Keep a steady hand when doing this, your meter should read about 190 volts DC, which is adjustable using the nearby potentiometer.
again be very careful, but if in doubt you can check the same voltage on any of the displays themselves, but this doesn't make it any less dangerous, proceed with caution IMO