Well I thought I've nothing to loose so I started taking it apart.
I got to the gears and everything was moving freely, which is wasn't before. I then had a look at the lens and the segments that come out when it focuses, only to find that it was all seized up there. So i took that apart, cleaned it and tried putting it back. It was still stiff so I lubed it up with some grease, we are only talking a very, very small amount. It free'd it up and I put it all back together and .......... It works !!!
It doesn't go through its full focal range but it certain works up to around six inches away and it focuses crisply. I may well take it apart again as it is no doubt something in the lining up by me on putting it back together. Even if I can sort it out I'm happy with that for the moment.
Another success as I also today managed to fix my sons PS3 by putting a new Blu ray drive in at a grand total for the fix of £31.