MPX shipped to SIG last Monday. MPX delivered back to me today (Monday). Just test fired it in the yard, and it functioned fine. Put back in/on my aftermarket brace, optic, and LaRue trigger group.
Paperwork says, "Inspected the pistol, replaced the bolt carrier, firing pin and spring, extractor spring and gas valve, test fired with no malfunctions."
No idea why extractor spring and gas valve were replaced, but new parts are fine with me. Will probably re-sight it in this afternoon. I'll also be ordering an aftermarket firing pin and spring to keep on hand.