Despite “Inherit Permissions” setting files revert to drwr-r- after save

I apologize if this is longer than necessary. But I’m erring on the side of caution and including anything that I think might be relevant.
I’m having a strange problem with Workgroup Manager and in particular with the “Inherit Permissions” setting.

Setup is: OS X Server 10.3.9 running on a 350 MHz PowerMac G4 (AGP Graphics) with 1GB of RAM and a WiebeTech RT5 RAID array, running hardware RAID 5 across four drives with hot spare. The RT5 is connected to the G4 via FW800 through a WiebeTech FireWire PCI card.

AFP and Windows service is running with 9 Mac clients and one Wintel box.

Original installation of Panther server 18 months ago was onto new, formatted internal drive. Data was on five old LaCie SCSI drives, full of mostly Illustrator 8 files. Workstations have converted to OS X and Adobe Creative Suite over the last 18 months.

Has been running fine for this 18 months, during which time I added a single firewire drive and rearranged some share points in Workgroup Mgr. No problem with that change.

This problem started when I added the RAID array and retired the single FW and SCSI’s two weeks ago. The array came pre-configured for RAID 5, and Mac-tested and formatted from WiebeTech. I changed the name of the volume from “WiebeTech” to “WiebeTech RAID.”
Copying of data from SCSI drives to RAID array went without incident.

Went through and re-created all share points, because the data in all of them had been moved. Some shares that were old SCSI volume names are now folder names at the root level of the RAID volume. Some shares were already folders and not volumes and were just moved.

All shares had always been set with “Inherit Permissions from Parent” so permissions were 777.
When recreating the share points I forgot this step and left the default “Use standard UNIX behavior” selected.

When I first became aware of the designers encountering read-only files, I changed, through the Get Info box, the permissions of the RAID volume from rwr-r- to rwrwrw.

This didn’t help, so I got some help from another consultant and we cleaned up a superfluous group called “employee” I had in there, changed the Protocol setting to “Inherit Permissions from Parent” and did the following in the command line:
sudo chgrp -R staff /Volumes/WiebeTech\ RAID

Then to fix permissions:
sudo chmod -R 777 /Volumes/WiebeTech\ RAID/

Now, when you look at files they are correct, with drwrwrw. But, as soon as someone opens the file and makes a change, permissions revert to drwr-r-.

As a temporary workaround there is a Crontab in place that runs the following every five minutes:
sudo chmod -R 777 /Volumes/WiebeTech\ RAID
But that takes a fair amount of processor time for a 350 MHz G4.

It doesn’t seem that Workgroup Mgr. is doing what it should. Any ideas?