The first thing found upon disassembly was that both lockplate anvils were failed. The anvil is what the tumbler stops against when released by the sear and, as you might imagine, it takes a beating (literally).
After annealing the lockplates, the broken areas were prepped and TIG welded up in preparation for reshaping.
The anvils were filed to shape and the interior surfaces were polished in preparation for case-hardening. Since the gun exhibited no case hardening color externally, the colors were removed from the exterior surfaces in order to render the repair externally undetectable.
Completed left lock