As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING FLIGHT NR 3460 OUT OF MSP, CAPT''S ALTIMETER FAILED RIGHT AFTER LIFT-OFF. AFTER LANDING RED OFF FLAG DISAPPEARED, HOWEVER WHEN ALTIMETER SETTING MOVED OFF CURRENT READING RED FLAG RETURNED. AIR RETURN TO MSP. MAINTENANCE REPLACED NR 1 ALTIMETER P/N 4039892-909, SN/ON 97054077, S/N OFF 99074747. NR 1 ALTIMETER OPS CHECK GOOD.