Sync loss can be recorded into source masters when there is a signal routing failure during production. It is sometimes caused by cabling between switchers or switched equipment missing reference. When two sources aren’t properly referenced to a sync generator, sync loss occurs when switching between those sources. It is visible as a loss of vertical hold in the image during the switching interval. Faulty cables or connections between source and record VTRs can also produce a loss of sync.
Can it be fixed?
There is no remedy if the sync loss is recorded in the source video. If the sync loss is occurring due to a video playback system failure, then maintenance or re-routing of the video signal is required.