VOR NAVIGATION NEEDLE STUCK RESULTING IN ACFT OVERSHOOTING INTERSECTION.

Narrative

DEPARTED RICHMOND ENRTE TO JFK. CLRNC WAS RIC 074 DEG R TO MODEL INTXN; THEN UP V33 TO COLIN INTXN. MODEL IS APPROX 34 MI FROM RIC; BUT THE DISTANCE ISN'T DEPICTED. THE ROUTE GIVEN KEEPS YOU CLR OF R4006; WHICH IS JUST E OF MODEL INTXN. THE F/O WAS FLYING AND WE WERE PROCEEDING ON THE RIC 074 DEG R. I HAD THE CROSS RADIAL (HCM 010 DEG R) SET IN MY NAV RECEIVER. THE COPLT HAD ASKED ME AT THIS POINT WHERE THE MODEL INTXN WAS LOCATED IN RELATION TO HCM. I REPLIED IT WAS 17 MI N OF HCM. AT THIS POINT I BEGAN MAKING A STANDARD PAX ANNOUNCEMENT TO THE PAX. SHORTLY AFTERWARDS THE COPLT MADE A HARD TURN TO THE LEFT. APPARENTLY THE VOR NEEDLE HAD STUCK AT FULL DEFLECTION SHOWING WE HAD NOT ARRIVED AT THE INTXN OR EITHER THE VOR WAS GIVING ERRATIC SIGNALS. ANYHOW; THE NEEDLE SWUNG FULL SCALE DEFLECTION IN THE OPP DIRECTION INDICATING INTXN PASSAGE. THE HARD LEFT TURN WAS TO CORRECT BACK ON COURSE AND TO AVOID R4006. AS PREVIOUSLY STATED; I WAS MAKING A PAX ANNOUNCEMENT DURING THIS BRIEF EVENT. THE COPLT ASSURES ME HE REMAINED CLR OF R4006 AT ALL TIMES. MY CONCERN AND THE REASON I'M MAKING THIS RPT IS THE FACT THAT HIGH SPD ACFT OPERATING ON THIS CLRNC HAVE ALMOST NO MARGIN FOR ERROR DUE TO THE CLOSE PROX OF R4006 TO MODEL INTXN. IF HCM VOR HAS A SCALLOP IN THE ARWY OR IF THE ACFT'S NAV EQUIP WOULD MOMENTARILY MALFUNCTION; YOU COULD EASILY MISS THE TURN AT MODEL AND ENTER R4006. MY RECOMMENDATION IS SIMPLY TO DEPICT THE DME FROM RIC TO MODEL ON THE 074 DEG R ON ALL CHARTS AS A BACK UP AND FOR XCHKING.