Thank you so much for that. I have only just put the computer on ! Will have a go at what you say - my husband will do it ! He not here at the moment, but I will get back to you at some point in the next few days.
My husband did what you said with the compressed air, but there was no difference. We are waiting for the cleaner now off a friend and see what that does.
It was very useful to know what the problem was in any case.
Thanks, ***** *****