As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED CONSTANT SPEED DRIVE RISE WAS OFF THE SCALE HIGH ON THE LEFT ENGINE. FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. REPLACED LEFT CONSTANT SPEED DRIVE AND GENERATOR. SYSTEM GROUND CHECK NORMAL OPERATION.