COMMUTER ACFT HAS CLRNC CONFUSION DUE TO FREQ CONGESTION AND RWY CHANGE. LNDG GEAR PROB FORCES GAR.

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BEFORE XING SEAL BEACH VOR THE FO ADVISED HE WAS OFF FREQ. DURING THAT TIME; APCH ISSUED HEADING AFTER VOR FOR ILS APCH. I THOUGHT THAT RWY 25L WAS TO BE EXPECTED AS VISUAL FROM THAT DIRECTION OF ENTRY. APCH ISSUED TFC TO FOLLOW. TFC WAS LOCATED BUT THEN LOST AFTER ENTERING CLOUDS. FO HAD ALREADY RETURNED TO FREQ AND ADVISED TFC LOST. I BECAME CONCERNED AFTER BEING GIVEN A HEADING TO INTERCEPT LOC THAT THE TURN WAS TOO LATE. AN APCH CLRNC WAS GIVEN FOR RWY 24R BUT; BECAUSE OF RADIO CONGESTION; I WAS UNSURE WHO IT WAS GIVEN TO. I ASKED THE FO TO RECEIVE CLARIFICATION AND INTERCEPTED THE RWY 25L LOC AND MAINTAINED 4000 FT. IT TOOK SOME TIME FOR THE FREQ TO CLR (APPROX 30 SECONDS) AND THEN ATC TOLD US TO TURN TO HDG 270 DEGS TO INTERCEPT RWY 24R LOC AND DSND TO 2500 FT; CLRED FOR RWY 24R ILS. ATC THEN ASKED IF WE COULD MAKE THE APCH FROM THAT POS AND WE CONFIRMED WE COULD FROM APPROX 11.5 DME. AT ABOUT 8 DME WE COULD SEE THE FIELD AND THAT WE WERE ON LOC AND GS. THE LNDG GEAR WAS EXTENDED AND THE R MAIN GREEN LIGHT FAILED. WE CYCLED THE GEAR BUT WERE UNABLE TO REMEDY; SO A GAR WAS INITIATED AT ABOUT 600 FT. WE ADVISED TWR AND WERE SENT TO APCH DURING WHICH TIME A LIGHT BULB WAS REPLACED AND THE LNDG GEAR LIGHTS WERE FUNCTIONING NORMALLY. ATC VECTORED US FOR ANOTHER APCH AND WE LANDED WITHOUT FURTHER INCIDENT.