The executive load is the software that resides in the FMDC. It is backed up by those 4 AA batteries you changed. You did change them with the control ON? That way you do not lose the data.
If the FMDC does not have this software, it loads it from the floppy. Thus the problem string could be data on the floppy or communications from the mother board to the FMDC. The status LEDs do change state from a ready to receive status to a loading status. There is a function key on the Bridgeport main screen when the machine boots for reloading the executive. It is F9 or F10, if I remember.