Hi again All,
Again, many thanks for your contributions - especially Joe.
Well, I continue to live and learn - hopefully other readers of the Forum will also benefit.
As I touched on earlier, the markings on the drive sprocket are so well sculptered, I had taken it that they were deliberately manufactured to contain the chain and stop it sliding sideways. Yes it would have been nice if the mower shop had looked at the sprocket - in fairness to them they were not mad about supplying bits for a 30 year old saw and told me up front that they were unable to do any work on it as it is not braked.
Joe, I have found the joining link and it is free. I have talked to the mower shop again and they dont have a replacement sprocket. I could run the new chain so it cuts its way into the worn sprocket but (not surprisingly) I want to replace the sprocket, which is welded to/part of the clutch drum on the McCull 10-10. Already got the old part off.
I have asked Bruce if he can supply this part but if he cant and anyone can help please let me know.
Kind regards