Fix Audio Drift in Interviews

I recorded fifteen short, sit-down interviews (each between five and eight minutes) and discovered that the two lav-mic tracks slowly drift out of sync with the picture, even though every file was captured at 48 kHz and identical frame rates. The amount of drift isn’t identical from clip to clip, so Final Cut Pro X’s automatic sync isn’t holding.

All I need is clean, sample-accurate alignment of the existing video file with its two corresponding WAV tracks for every interview—no extra cuts, transitions, colour work, or effects. You can work directly in FCP X or in any NLE you prefer as long as you return either an FCPXML I can relink or individual, fully synced video files.

Once the audio is locked to picture without any perceptible slip from start to finish, the job is done. I would also like you to teach/share with me your solution (other than manually lining the tracks up because that's what I have been doing).