Problems viewing Hi8 tapes

Hi I have two hi8 tapes which I taped some vacation and wedding footage about a year and two years ago respectively. I use a Sony camcorder (TVR 280 model), and previously (a couple months ago) the tapes were playing back and showing the pic and audio in the viewing panel of the camcorder. Recently I was checking back on the tapes though, and neither of them were showing or giving audio on the panel...the screen just looked blue. I checked the camcorder itself and when I have it on camera mode, the lcd screen shows whatever is in front of the lens, so I ruled out the screen as the problem.

Can you tell me what can be wrong? Is it the tape or the camcorder?

Thanks