I have run the Header Tape through a couple of times (I just followed instructions that came with the pack). There had been one or two error symbols on the camcorder indicating that the headers needed cleaning and they have now disappeared, so the headers probably needed cleaning anyway.
Still, the problem persists. There are two lines across the 'pull-out' screen and as the tape is playing I notice that every few seconds or so the sound and video 'jumps'. This happens with every tape played.
I am not quite sure what the cause of these 'two lines' could be or how to resolve the problem.
There is another possibility that I have seen in the past with the tape based cameras. If there is still some kind of blockage that is causing these lines on the screen you could try turning the camera upside down and giving it a few firm taps with your hand. I know that this sounds like bizarre advice but I have actually seen it work for some users in the past (it usualy helps to get rid of error messages etc but you never know).
If that still doesn't resolve the problem, it may be time to find out how much a repair would cost. There is a sticky forum thread about contacting customer services here:
Having said that, you may find a better price by asking around some local repair centres and there may also be companies online that are able to repair your camera provided that you are willing to ship it to them. If you put 'camcorder repairs' into Google, you will see a few possibilities.