All I have sorted it! I opened the Amiga up and my Mrs gave it a clean with a soft make up brush and now it saves fine! So it was just very dusty.
I'm so relieved. Thank you all for taking the time to reply and try and help me out.
Sounds to me like your Amiga just wanted a good tickling with a makeup brush! My 2nd thought was use of HD Floppies (extra hole located opposite the write-protect hole). AT A1200's were fitted with modified PC HD floppy drives and those drives do not permit the use of HD floppies as DD floppies unless you tape over the extra hole.
When my A1200's floppy died in the mid 90's I got a replacement drive from Gordon Harwood computers in Alfreton, Derbyshire. This drive had the same issue. You can always spot these replacement modified drives as they have a green led activity light on the actual drive.
