Thank you James
You are of course correct. I do have the setting on 15px but was under the impression this is how I had to set them up to stop blurring due to something that was indicated in a right click on 'inspect element'. I did have the hard crop box ticked, so am assuming that if I uncheck that they'll return to something close to a default size? Other than that I suppose I could just play about with it putting a different specification in until such time as they display?
I'll have a muck about and see where it takes me