PRIVATE PLT INADVERTENTLY DSNDED EARLY DURING AN INST APCH DUE TO A MALFUNCTIONING VOR RECEIVER.

Narrative

I WAS FLYING THE LOC BACK COURSE RWY 4 APCH INTO TEXARKANA. I HAVE BEEN HAVING TROUBLE WITH THE VOR STICKING AT FULL DEFLECTION. WHEN I WAS HANDED OFF FROM ZFW TO TEXARKANA TWR; I THOUGHT THE CTLR ADVISED ME I WAS 4.6 MI FROM THE ARPT. WHEN I LOOKED AT THE VOR TO SEE IF I WAS ON THE 170 DEG RADIAL FROM TXK; IT WAS AT FULL DEFLECTION SO I THOUGHT IT HAD MALFUNCTIONED. SO I STARTED MY DSCNT OUT OF 2000. THE VOR THEN JUMPED TO THE MIDDLE AND I REALIZED I MUST HAVE MISUNDERSTOOD THE CTLR SO I IMMEDIATELY INITIATED A CLB BACK TO 2000 FT SINCE I WAS NOT AT THE FINAL APCH FIX YET. AFTER I INITIATED MY CLB THE TWR TOLD ME THAT CTR ADVISED ME TO STOP MY DSCNT. I THEN EXPLAINED TO THE TWR WHAT HAD HAPPENED. I LEARNED THAT YOU MUST BE 100 PERCENT SURE OF WHAT CTLRS TELL YOU AND THAT YOUR EQUIP MUST ALSO BE 100 PERCENT. IF YOUR INSTS DON'T ASSUME ANYTHING; ASK FOR VERIFICATION. I BELIEVE THIS EVENT HAS MADE ME A BETTER PLT. I FIND THAT I AM MORE ALERT AND AWARE OF EVERY SITUATION. IT IS UNFORTUNATE THAT THIS HAD TO HAPPEN; BUT I'M GLAD SOME GOOD CAN COME OUT OF IT.