Thanks Martin for your reply. I have now dismantled the assembly after taking lots of photos and removed the offending lower coil. It wasn't hard to find out what had happened....and it would have to be the inner/start of the winding.
See photo. Fortunately I have been able to measure the winding = 230 ohms so at least there aren't any other breaks. I am going to see if I can 'lasso' that end and solder on another wire before I have to resort to unwind the coil and redo it. Nothing ventured, nothing gained eh?
However I think on reflection that a rewind would be best and definitely the more reliable option. I'll report back once I've got it sorted.