My issue with audio dropping out and frame loss was due to media. I used panasonic PQ 63 minute tapes and 3 out of 3 with zero dropped frames.
Previously I used Sony Premium 60 minute and would get 2-10 dropped frames. Sometimes i would recapture the same tape and it would pass a section that previously dropped out with out incident, then drop in a new section. Other times, like clock work, it would drop out at the exact same locations. Making it difficult to trace down and very frustrating!
May be you will have better results with Panasonic PQ.