All tapes in your setup (both audio and video) must be striped with SMPTE Timecode before any audio is recorded onto them or to Pro Tools. If tapes aren’t striped, your system may seem to work, but synchronization will never properly occur. The machines and Pro Tools will drift farther and farther apart the longer they run.
The same problem occurs when audio is recorded into Pro Tools without a resolved SMPTE source (for example, if it was recorded before the current session). The audio cannot be accurately synchronized with an analog tape recorder or video tape deck, since the Pro Tools audio was not recorded referenced to the SMPTE timecode from the analog tape deck or video tape deck.