I'm saying that due to the hardness of the material, a stress fractured or broken sear can't be fixed. A gun smith can Pep Boy the thing, but not properly repair it.
And we are talking very hypothetical here. I've never seen a auto sear break or wear out.
BTW our store just got .40 S&W and .45 ACP UMP samples. I'll post pics as soon as we shoot them. Got to test them before giving them to the PD.
Don't know if they will come back intact from the demo.