As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT LEVEL OFF FL330 ALT DISAGREE EICAS LIGHT CAME ON. CAPT ALT READ 300 FEET DIFF FROM F/O ALT. AFTER DESCENT TO FL280 CAPT ALT READ 28010, F/O ALT READ 27760 STDBY READ 28350. PER FIM REPLACED F/O`S ADC AND CHECKS NORMAL. OPS OK PER M/M. ALSO REPLACED F/O`S ALT IND AS PRECAUTIONARY.