Many thanks for this. Much of it confirms what I had already thought. Two further points arise, however: 1. How do I (easily) open one of these machines to photograph the DVD drive and will I know which bit it is inside the machine? 2. Regarding the correction of a scratched disc, the machine will not allow me to withdraw the faulty disc before it has 'corrected' (i.e. usually ruined) it. How can I extract it before this happens?
P.S. Once these particular issues are sorted, please be kind enough to cancel the direct debit which I believe was set up before I could get any answers!