Audio suync issue on FW playback

I am using FCP5.0.4 on a G5 tower dual 2.7 GHz with 1 GB DDR SDRAM.
Running OS 10.4.8

FCP plays out through a JVC SR-VS30U mini DV deck and NTSC monitor.
I have audio and video set to playbck through FW through this deck and monitor.

I recently imported a finished project back into FCP to make some minor adjustments and re-export as files for someone else to work with.

As I began to look over the clips I noticed that the audio and video are out of sync.
I have split the tracks to begein re-syncing - a pain but no big deal.
And, I am wondering...
Should I set my auido to playback out of the G5 and check its sync with what I see in the viewer window? Or should I leave it set to playback externally through FW and check on the monitor/deck setup?

I am thinking that I should check the clips in FCP itslef, but then are there any computer issues that might cause this sync issue that I may not be aware of?

Any suggestions will be gladly accepted.