As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SEA - IN CLIMB AND CRUISE, NOTICED THE AIRCRAFT WAS SHAKING NOTICEABLY AT 850 RPMS. WERE NOT IN ICING AND DID NOT NOTICE ANY SHAKING AT 900 OR 1020 RPM'S. THE SHAKING WAS GETTING TO THE POINT WHERE THE NR 2 PFD AND NR 2 MFD WERE BLURRY. NR 4 BLADE ON NR 1 PROP REPLACED. C/W SIX BLADE RETORQUE OF NR 2 PROP. RETURNED TO SERVICE.