I saw another thread that applied to my GR70U. It involved taking off all screws on the exterior case (make note of where they come from, as their sizes differ), and performing a hard-reset of the camera. The hard-reset apparently occurs when you disconnect the connector at the thumb button for five minutes. Check the thread if I have this incorrect. Mine worked just by taking the screws apart and re-assembling the unit. Also, some users have reported that the condensation occurs from using a tape with moisture. This is what is causing the sensor to go. One other poster on this thread reported that the sensor was faulty and simply bypassed it -- well out of my skill-set. Try changing tapes first before getting exotic.

The loading motor bracket assy has the dew sensor on it that causes that problem. I have several in stock, it runs 14.95 + 3.95 shipping