What was found
AIRCRAFT WAS GROUNDED: --DECISION WAS MADE TO DIVERT TO IAD. EMERGENCY DECLARED; AIRCRAFT LANDED WITHOUT INCIDENT. ON APPROACH INTO DCA, RT MAIN GEAR GREEN LIGHT WOULD NOT COME ON PAST 45 SECS. ONCE WE PUT THE TEST LIGHTS ON, THE LIGHT ILLUMINATED, THEN STAYED ON. CYCLED THE GEARS 2 MORE TIMES, AND IT WAS THE SAME THING; LIGHT WOULD NOT ILLUMINATE UNLESS WE PUT THE TEST LIGHT SWITCH TO ON. THIS WOULD TAKE OVER A MINUTE. T/S IAW FIM 32-09-00-810-805 AND FOUND MTC MSG 32-01005. FOUND NLG PROX SENSOR S1015 OUT OF RANGE. ADJUSTED SENSOR IAW AMM 32-09-02. OPS CHKD GOOD. WHILE T/S FOUND RH MLG INDICATOR LIGHT WITH INCORRECT BULB CAUSING INCORRECT INDICATIONS. R/R RH MLG INDICATOR LIGHT BULBS IAW SWPM 20-84-18.