As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INBOUND TO SFO AND JFK, WHEN EXTENDING GEAR GOT NORMAL INDICATIONS FROM NOSE AND RIGHT GEAR. GOT EICAS GEAR DISAGREE MESSAGE AND NO LEFT GEAR INDICATION FOR APPROX 5 SECONDS. FINALLY LEFT GEAR GREEN AND EICAS MESSAGE WENT AWAY. *S/D* REPLACED LEFT MAIN GEAR RETRACT ACTUATOR. (PART OFF WAS MR32387-11).