You need to use your Control Diagrams 9120xxxxy to figure out the test points to measure the Brake Voltage going to the Z-Brake after the drives are started with no Foldback.
If you reloaded the machine parameters or switched the software without making a backup *.BCK file; then you may have lost them.
This could cause improper drive settings in the control that could cause the drives to imbalance a nd shut down with an Overcurrent (Foldback) Alarm.
Uninstall backs up the current Machine Data Parameter file onto the hard drive; but if you did other things before it may have been wiped or corrupted.
Talk to Biil-O who retires End of June....