Hello Rob,
I don't think the leader can be repaired, as the used polymer doesn't
react well with glues, simply out will not be robust enough.
But if you have some patience and a sharp knife, topi can cut out new
leaders from black plastic layers, I used old X ray films of the bones.
I did it for all of my drives (only had broken at start), and it worked.
For me it was tricky to find the right shape of the original leader, but
you have the damaged one...
Andrea