As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ENGINE SHUTDOWN PILOT MOVED THROTTLE TO CUTOFF AND THERE WAS NO RESPONSE. SECOND ATTEMPT WAS MADE WITH SAME RESPONSE. PILOT NOTED NG SLOWLY INCREASED TO 63% AND IMMEDIATELY SHUTDOWN ENGINE USING FUEL SHUTOFF VALVE SWITCH. MAINT NOTED THAT THROTTLE LINKAGE HAD BROKEN.