As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PER CREW VERBAL AIRCRAFT SPEED WOULD NOT ADVANCE PAST 270 KTS. AIRSPEED WOULD ALSO NOT TRANFER OVER TO MACH. FOUND ALTERNATE VMO/MMO SWITCH IN THE ALTERNATE POSITION. PLACED SWITCH IN NORMAL POSITION AND VERIFIED ADR LABEL 270 BIT, REF AMM 57-31-21-400-802 AND 34-21-00-730-802