Before you dismantle the iBook, did you try a PRAM and NVRAM reset?
Thanks, Applemacaster: just did that and has not made any difference to the lines.
PS: Never lost anything else like time etc: so, I guess, I must have had those OK!
You can either give it back to apple and let them change it or do the job yourself although it involves totally stripping down the iBook
Jet II: Once upon a time about 20 years ago today, when the Mac had started selling here with inadequate Tech support, I had got the special screw driver made to open and service etc my own Macs. However, this laptop is another matter and I do not feel that confident of being able to hack it myself! Maybe it is got something to do with the fact that when you are younger, you are willing to try on any dare -- or some such! Thanks, anyway. I shall toodle across to the Mac shop and see if they can look at it.
You can replace the screen, or use an external display.
Unhinged: The option of changing the screen is not really there. This being a four+ years old model, the spare backup is quite minimal here. I suppose if I insisted, the local Mac shop would obtain it for me from Apple, but, I suspect, that may cost me a horrendous amount: might just be wiser to add a bit and buy a new Mac Book! As for the second part: Yup, that is what I intend to do after I have got myself another lappy: use this one as a desktop with a TFT screen.
Thanks very much, all of you!