In reply to Fraser: Hey Fraser, technology has the terrible habit of doing exactly what you tell it to do, even when you've forgotten what it was. I once took a series of photos with flash at iso 1600 in manual mode, and it was only after taking a series of two or three groups that I realised. I was very shamefaced getting the groups back together again in order for me to take their pictures properly. As I get older, I find new ways to duff up. I'm sure there's been threads about this before from other oafs like me as well.
Anyway, I didn't reply to tell you what an eejit I was. Go to Johnstones Camera Repair in Glasgow and they will be able to sort any problem you've got. They're reasonable and if they think they can sort your problem, they almost certainly will. I've taken my cameras and lenses and flashes for repair and service there.
Awrabest
Tom