What was found
GEAR DISAGREE AFTER TAKEOFF AND HANDLE RAISED. LEFT MAIN REMAINED DOWN. RAN QRH TO GET ALL GEAR DOWN ***EMERGENCY DECLARED*** PERFORM SYSTEM BIT TEST OF PSEU DISPLAY 999 AND 000. PERFORMED SENSOR AND TARGET TEST ON SYS 1 AND 2 AND BOTH READS FAR. RESET SYSTEM AND PERFORMED TEST AGAIN WITH SAME RESULTS. VISUALLY INSPECTED SENSOR AND WIRING SAW NO DEFECTS. UNABLE TO CHECK TOLERANCE NOT HAVING A FEELER GAUGE. GEAR DOORS ARE UP AND LOCKED. INSTALLED MLG DOWNLOCK ACTUATOR REF AMM 32-32-02-4. OP CHECK GOOD, NO LEAKS. GEAR SWING ACCOMPLISHED REF AMM 32-32-00-5