Through what equipment and method do you play back the sound, and what settings and connections do you use? Are some channels more prone than others?
Using an audio setting of 'Stereo' and via HDMI and then letting a Sony TV output the sound itself or through an amp I very occasionally get out of sync immediately after there has been a reception blip. But otherwise my HDR-2000T has been fine so far.
I doubt if adjusting the lip-sync delay will work as those programmes which would have been OK will no longer be!
I have previously suffered from bad lip-sync constantly but if I used the TV's own tuners and speakers it showed that the TV was the culprit. I replaced the TV.