Hi John,
Yes, it is definitely Old English. The canes look Richardson ones to me but it is not my area of expertise. I am sure someone else will come along soon to confirm/infirm this identification.
Yes, some people had tried to have such cracks 'repaired' before (and as I understand it, it is indeed done by re-heating the weight - but I know little about this process). I have seen and handled a weight that had been 'repaired' in this way and it was far from perfect. In the weight in question, a line was still definitely visible. Sometimes air bubbles can get trapped along the crack too (especially in the weight actually broke into separate parts - which is not the case here).
SophieB