What was found
PILOT WAS PERFORMING PRE-START CHECKLIST FOR 2ND FLIGHT OF THE DAY. WHILE OPERATING NR 2 TWIST GRIP FROM "0" TO "F" NOTICED EXTREME FRICTION FROM BETWEEN "30" AND "F". MADE SEVERAL ATTEMPTS TO GO TO "F" BUT WAS CONCERNED THAT SOMETHING MAY BREAK. ACFT REMOVED FROM SERVICE. TROUBLESHOT. CONTINUED DISCONNECTING CABLE ENDS AND ISOLATING UNTIL N1 CONTROL BOX REMAINED. REMOVED N1 CONTROL BOX FROM ACFT AND CONFIRMED THAT THE NR 2 ENG SECTION IS BINDING APPROACHING "F" THROUGH "EMER" RANGE. ALL OTHER CABLES AND TWIST GRIPS OPERATE SMOOTHLY.