What was found
(CAN) ON APPROACH, THE CREW EXPERIENCED A GEAR DISAGREE MESSAGE ON EICAS AFTER SELECTING THE GEAR DOWN. IT WAS REPORTED THAT 6 UNSUCCESSFUL ATTEMPTS WERE MADE TO EXTEND THE GEAR VIA THE NORMAL SYS. EACH TIME THE NOSE GEAR WOULD EXTEND NORMALLY BUT BOTH MAIN GEAR WOULD NOT DISPLAY DOWN AND LOCKED. THE MAIN GEAR WERE SUCCESSFULLY EXTENDED USING THE ALT EXTN METHOD. A LATER REVIEW OF THE FDR INDICATED BOTH MAIN GEAR DID NOT RELEASE FROM THEIR UPLOCKS. MX WAS ABLE TO DUPLICATE THE PROBLEM IN THE HANGAR. REPLACEMENT OF THE MLG SELECTOR VALVE RETURNED THE GEAR TO NORMAL OPERATION.