I have a Panasonic NV-DS60EG and had the same problem. Within 2 years i needed twice a new dew sensor . Now for the third time it happened again. No more guarantee. Grrrrr. But something strange happened. When you open the lid( tape side) you see in the middle a black pin with inside a transparrent part. That's the dew sensor. I don't know how it happened, but i cleaned the sensor with a soft tissue and pressed a bit i hope to make a better connection.... and see, the camera worked again. Yipeeee ! Mark from Holland.

Ral, the 1k resistor worked a treat - many thanks!

Thanks Ral, I'll try that. I was thinking about using a resistor but wasn't sure what value.