What was found
AIRCRAFT WAS GROUNDED: DURING LANDING GEAR RETRACTION, LANDING GEAR HANDLE APPEARED TO BE LOCKED IN THE DOWN POSITION. AFTER 3 ATTEMPTS, ABLE TO RAISE THE HANDLE. MAINTENANCE ACCOMPLISHED TSM 32-31-00-810-885-A AND FOUND FAULTING NR 1 LANDING GEAR CONTROL INTERFACE UNIT, NO DC VOLTAGE AT PIN W, CONTINUITY CHECKS SUCCESSFUL FROM LANDING GEAR CONTROL INTERFACE UNIT NR 1 TO LANDING GEAR SELECT HANDLE (6GA). REPLACED NR 1 LANDING GEAR CONTROL INTERFACE UNIT PER AMM 32-31-71 AND PERFORMED SUCCESSFUL OPERATIONAL CHECK WITH NO FAULTS.