What was found
DFW/ASE - FLT 429 - WHILE IN CRUISE AT FL 310 WITH OAT - -46 C, NOTED NO RESPONSE FROM LT PWR LEVER. WHEN ACFT REACHED FL 280 (OAT - -35 C). AFTER NUMEROUS ATTEMPTS TO FREE LEVER, LEVER BECAME UNSTUCK. ACFT CONTINUED TO ASE. MX GROUNDED ACFT AND INITIATED SPR 8210 TO FAIRCHILD/DORNIER REQUIRING MORE PROCEDURES. MFG ADVISED C/W ASB 76-15 COUPLED WITH ADVISE TO CREWS TO MOVE PWR LEVERS EVERY 20 MINS TO PREVENT FREEZING. MX PERFORMED INSP OF PWR LEVER CABLES, LUBED CABLES IAW ALERT SB 328-76-015. ASB 328-76-015 C/W ON 12-11-97 AT TAT 7203.7; 58.1 HRS PRIOR TO INCIDENT. ALL 328 DISPATCH RELEASES MODIFIED EFFECTIVE IMMED TO HAVE CREWS MOVE POWER LEVERS EVERY 15 MINS. ACFT RTND TO SVC. PART TC: 9,673.(X)