Unless it's just the pic,,the support for the frizzen on the pan is bent way over. The lock can be seen off to the right in the pic.
I'd fix that problem first. Do whatever alterations necessary to allow the frizzen to have ample support metal around the pivot screw hole.
Then cut the old broken axle support area off of the frizzen.
Clean up the cut off area, square it up, fit in and braze on a new piece of steel.
Wide and large enough to make a clean, square supporting surface with the plate and pan.
Then drill a new frizzen screw hole.