Thank you for your reply.
No, I have not used a lens cleaning disc mainly because from what I read on various forums this is not recommended by the manufacturers.
Also, I considered that as the unit has only had minimal use it should not have become that dirty - I've only played one CD and that for only half an hour per day.
Do you think I should purchase a lens cleaning disc, or could there be another fault?
I have purchased an Allsop Prolens Cleaner and this also skips (there is a commentary on the disc).
I then inserted the original CD and it 'reads' the disc for about two minutes (showing - 'READING' on display), then says 'NO PLAY'.
I think the unit is now destined for the rubbish bin - I've spent enough on problem solving.