In response to my own posting here from last month, let me tell you how I solved the problem, in case others have the same one. I had tried fully charging the battery, and also tried a new replacement battery, it didn't solve the problem. But today, on a whim, I tried recording and playback with the unit plugged directly into the power adaptor, no battery -- and it works! So, somehow, the batteries were allowing me to record, but not playback. Makes no sense, but it works.

In response to my question posted at http://www.pechorin.com/m/2005/10/01/JVC_DVL300_Blue_Screen_of_Death-246526.html , Stacy Sample, JVC Service Houston (see email address at the top of this thread), gave me the following helpful -- if unwelcome -- answer: I believe the drum has failed on your camcorder and to be completely honest...don't spend money on a repair. You can buy a really nice camcorder for just around what a repair would run and have more functions. Check out these models first before you decide to repair this one. There is a cool site called BuyDig.com and you can get a new camcorder comparable to yours or spend a few dollars more and have more functions.  Also you can get a 4 year parts/labor ext warranty for $59.99 more. I believe this would be best for you. Take a look and let me know what you decide.