Given the modular design of the CFM56, LEAP, and virtually all modern engines, after the initial surge, there would seem to be little benefit in shipping whole engines back to manufacturers for the limited teardown required for this inspection.
I'd expect that the GE crew in Seattle could remove, ship, and swap LPT modules quickly; This places less risk to the rest of the engine hardware. (I'm speaking of ground shipping damage, of which I've seen more than a little)
