when it faults
do the contactors attempt to engage
or is it a case of step on pedals and immediately 48 comes up,
or as mentioned a pmt trip, (which feels like someone just bumped into you)
if you can get it to come good without cycling keyswitch or unplugging battery, that elliminates PMT trip, as that is the process to reset a PMT trip
suppressors on the contactors depended on the year of the machine
does turning the steering, whilst running on blocks make it worse or not, steer position switches have been known to trip the cards, but will need power cycled to reset
have you disconnected and tested the large capacitor on the ev100 panel