INST RATED PVT PLT OF A C182 DSNDED BELOW ASSIGNED ALT PRIOR TO ESTABLISHED ON FINAL VOR COURSE DUE TO DISTR OF THE FAULTY INDICATION OF THE #1 VOR NAV COURSE INDICATOR AND DIALING IN THE #2 VOR NAV RECEIVER. RPTR WAS ABLE TO SALVAGE THE APCH AND LAND UNEVENTFULLY.

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I WAS ON AN IFR FLT PLAN FROM THE BAY AREA TO SANTA MONICA (SMO). I EXPERIENCED INTERMITTENT PROBS WITH THE XPONDER AND #1 NAV RADIO. THE FLT WAS FAIRLY UNEVENTFUL UNTIL APCH INTO SMO. WHILE BEING VECTORED FOR THE VOR APCH TO RWY 21; RADAR CONTACT WAS TEMPORARILY LOST RESULTING IN A LATE VECTOR TO INTERCEPT THE FINAL APCH COURSE. I WAS CLRED FOR THE APCH AND TOLD TO REMAIN AT 3000 FT MSL UNTIL ON COURSE. I TURNED R TO INTERCEPT THE COURSE. THE NEEDLE ON THE #1 NAV REMAINED PEGGED TO THE R EVEN AFTER I WAS CERTAIN I HAD FLOWN THROUGH THE FINAL APCH COURSE. I BEGAN A SLOW TURN TO THE L HOPING TO REINTERCEPT THE APCH AND COMMENTED TO MY PAX THAT THE RADIO APPEARED TO BE MALFUNCTIONING. THE NEEDLE MOVED TOWARD THE CTR AND I BEGAN A DSCNT. BEFORE THE NEEDLE HAD COMPLETELY CTRED; THE 'NAV OFF' FLAG SPORADICALLY APPEARED ON THE #1 NAV. I DIALED THE FREQ AND COURSE INTO THE #2 NAV BUT; DURING THE PROCESS; DEVIATED TO THE L OF COURSE AND WAS AT 2400 FT MSL WITHOUT ACTUALLY BEING ESTABLISHED ON THE FINAL APCH COURSE. THE CTLR ASKED IF I HAD THE ARPT IN SIGHT; TO WHICH I REPLIED AFFIRMATIVE. HOWEVER; IT WAS VERY HAZY AND I WAS UNFAMILIAR WITH THE AREA. I BECAME LESS CERTAIN THAT I WAS ACTUALLY LOOKING AT THE ARPT AND ASKED THE CTLR FOR A VECTOR. BY THIS TIME; I HAD TRAVELED CLOSER TO THE ARPT AND DETERMINED THAT I ACTUALLY DID HAVE THE ARPT IN SIGHT. I WAS CLRED TO LAND AND DID SO WITHOUT INCIDENT. IN RETROSPECT; I SHOULD HAVE HAD THE #2 NAV ALSO SET TO THE APCH COURSE WHICH WOULD HAVE ALLOWED FOR AN EASY SWITCH TO THE #2 ONCE IT APPEARED THE #1 NAV WAS NOT FUNCTIONING PROPERLY. ALSO; AFTER A LATE VECTOR TO THE FINAL APCH COURSE; I LET MY DESIRE TO 'CATCH UP' INFLUENCE MY DECISION TO BEGIN MY DSCNT PRIOR TO BEING FULLY ESTABLISHED ON COURSE. I WAS ALSO TOO ANXIOUS TO CONFIRM HAVING THE ARPT IN SIGHT.