found the problem which was preventing ntp client from running on the sei frontend. There was an entry in the /etc/ntp/step-tickers file (was a caltech address) so I had to add the GC NTP server's address to this file. Seems that if this file is empty, ntp would also work. I kept the ntpdate crontab running on the workstation (every minute) and that machine is time shifting a lot to keep up with the front end (shifts of 0.1 second every minute are common). Not sure what's up with that, I have now turned off the crontab and ntpd is running sync'ing with the GC server also.