<HTML>I have transferred some 30 hours of old Hi8 to miniDV, capturing directly from my Sony Hi8 to a GV-D900 and experienced no problems. It is great that I now have clean code MiniDV masters. I have not tried going direct to a MiniDV camera, is this the source of your difficulty? I only use Sony Premium Tapes, DVM60PR2.
I would suggest you clean the playback head and the record head and also check the seating of your cables plus the quality of your tapes.
I hope that, like the marine layer in Venice, your problem dissappears by noon.</HTML>