Hi,
I don't know what exact model servo and drive you have but this comes from the B2 series manual:
If L0003 corresponds to Al003 then that is an under-voltage alarm. This is surprising, I would have expected an over current alarm, AL001, or a following error fault, AL009.
First you need to check the manual for your drive, it may differ from the B2 manual.
It could be that as the load came on, ie the Z axis stalled that the increased current caused the input voltage to sag and thence cause an under voltage

alarm, but that would be unusual.
Craig