Hello. I own a Panasonic AG-EZ30UP that I bought from eBay a
little while ago. It was working very well until yesterday. Upon
playback of any DV tape there are large bold residual lines, and the
camera plays, but it plays behind these lines. This also occurs when
connected to a TV or a PC via firewire. It hasnt been dropped or
damaged. For taping it works very well and there are no problems, only
in VCR function. Thanks in advance.

Have you tried to clean the heads with head cleaning tape? If not, this may help you. If problem persist only way to go is service senter.