Hi. My name is*****’m a camera repair technician with over 20 years in the business and I'll be glad to help you with your question today.
If the lens fails to achieve infinity focus, the front element may have come loose. Check to see that it is screwed down tight. You may need to remove the decoritave decal ring around the edge of the front element to access the spanner slots used to tighten the element in place.
Many thanks for your reply. I admit to being a bit "miffed" because I thought that I was logged onto the official Nikon UK website as Googled. I am now aware of "Just Answer" and wiser about the internet. I am the wrong generation!. BUT, I bow to your experience and feel a bit of a plonker. A the moment I think that you are exactly right. The front element was slightly loose and the "in focus" indicator in the viewfinder is working again. I will check it all over again this evening to make sure that I have kept it clean but I think you have sorted it for me.
The score board has disappeared but I have no alternative to awarding you< "Excellent Service". Perhaps it would have cost me more than £22 if I had connected with Nikon.