Firstly, thanks guys!
I played a bit more with the drive last night and have an idea but it may just be chance. Last night I successfully burned a DVD-R with absolutely no scuff mark at all and looks perfect (Imation DVD-R 16x). This was preceeded with it scuffing a DVD+R (Verbatim 16x).
On looking in the drive, there is a connecting flat lead to the lens that is flexible to allow the lens to move. This connector is normally half tucked beneath the metal tray, but is currently slightly rising out of it. I think this is scraping the DVD+R Dvds which seem to write from the centre out, and its when the lens is at the centre it is scraping.
When the DVD-R is being used this is written (And read?) from the outside edge? Is this the case? And therefoer, the connecting wire is not in the same position and no longer scrapes.
Its my idea so far. I would agree the drive is not entirely happy but the laptop is out of warranty now and if I can get by with DVD-Rs thats fine! No CD or other DVD seems to be scratched, only the DVD+Rs!