Just an update on this one. Paris Dakar got it in one!!
Bought a head cleaning tape (£20.00 GBP!!!) and ran it through. Managed to get about 4 minutes of clear picture before it started to pixellate again. Another head clean and another 4 minutes and so on. Thankfully, the recording was only about 12 minutes but, as a safeguard against loss, I downloaded it onto two different computers AND a DVD recorder hard drive, so the cleaner has been well used.
Another query for the video buffs - If I burn the edited film onto a CD, rather than a DVD, should I be able to play it in the DVD player?
TIA