As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING RUN-UP PRIOR TO TAKEOFF, TACH WENT TO ZERO. FOUND THAT CABLE END SWAGE/NUT ON TACH INDICATOR END HAD PULLED OFF THE CABLE HOUSING. NEITHER CABLE END WAS SWAGED TIGHT TO CABLE OUTER SHEATH. NEW CABLE INSTALLED. NEW CABLE APPEARED TO BE SWAGED THE SAME AMOUNT. SUGGEST A TIGHTER SWAGE IF CABLE SHEATH WILL ALLOW IT.