I have a DCR-TR7000 that stubbornly refused to accept a video cassette showing in the viefinder the "droplet sign" for humidity/moisture error. I left it open for a whole night in a dry warm place. No good. I considered taking it appart as many of you suggested but I decided to try something else first.
I bought for 8 bucks a tuner aerosol spray intended for cleaning delicate electronic circuits that does not leave any traces behind. It is branded K600 and made in Belgium by Kontakt Chemie Ltd. (I guess there are many other similar products in hardware stores.) I sprayed sparsely into the open cassette holder and let it ventilate for a couple of hours, then drew air from the open camcoder with a vacuum cleaner for about 1-2 minutes.
Bingo - it works like new!