I bought a refurbished Sharp digital camcorder VL-WD255u on an online auction site. It records great, but the audio breaks up when you play it back. I sent it to the Sharp authorized repair place two different times. Both times they replaced the video head assembly, but the audio still isn't fixed. Have played the tape back on different TVs and the camera itself, but no change. The audio comes in and goes out. There's no static. Have recorded on new mini DV tapes, but that doesn't help. Any ideas what's going on here?