As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(OG5S) UPON LEVELING OFF FOR CRUISE FLIGHT CREW DISCOVERED THROTTLE COULD NOT BE REDUCED BELOW 2400 RPM. FLIGHT WAS ABORTED AND POWER OFF LANDING WAS PERFORMED. UPON INSP BY MX THE DISCHARGE TUBE FOR THE ACCELORATOR PUMP HAD COME LOOSE AND LODGED IN THE BUTTERFLY VALVE IN THE CARBURATOR. CARB WAS REPLACED AND ACFT RETURNED TO SERVICE.