What was found
SEA FLIGHT NR 9853: AFTER SELECTING GEAR UP, ALL ADVISORY LIGHTS ASSOCIATED WITH LEFT MAIN GEAR AND NOSE GEAR EXTINGUISHED NORMALLY. THE GREEN RIGHT GEAR LIGHT ALSO EXTINGUISHED NORMALLY, BUT ABOUT 10 SECONDS ELAPSED BEFORE THE RED RT GEAR, THEN THE AMBER R DOOR AND FINALLY THE GEAR UNSAFE LIGHT IN THE HANDLE EXTINGUISHED. FLIGHT DIVERTED TO PDX. MX INTERROGATED PSEU. FOUND RT MLG UPLOCK AT HIGH END OF RANGE. RIGGED PROX SENSOR RT MLG UPLOCK TO NORMAL GAP IAW Q400 AMM 32-61-06-830-801. PERFORMED EXTENSION AND RETRACTION OF MAIN LANDING GEAR IAW TASK 32-31-00-710-801. GEAR OPERATED NORMALLY. NO PARTS REPLACED. AIRCRAFT RETURNED TO SERVICE.