As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE LT ENGINE RPM GAUGE FAILED ON RUN-UP. DISCOVERED THE TACHOMETER GENERATOR P/N 22A667 DRIVE SHAFT HAD SHEARED. THE TACHOMETER GENERATOR WAS REPLACED AND AIRPLANE RETURNED TO SERVICE. THE TACHOMETER HAD BEEN OVERHAULED AND PUT BACK INTO SERVICE 3-29-96. TOTAL TIME SINCE OVERHAUL 1497.7 HOURS.