What was found
LEFT MLG LANDING GEAR RETRACTION: AFTER TAKEOFF, GEAR HANDLE SELECTED UP, ALL 3 GEAR WOULD NOT RETRACT. GEAR HANDLE REPOSITIONED BACK TO DOWN. GEAR STAYED DOWN 3 GREEN. NO CAS MSGS APPEARED. REMOVED DEFECTIVE LANDING GEAR MODULE & INSTALLED A CUSTOMER SUPPLIED OVERHAULED LANDING GEAR MODULE. PERFORMED MULTIPLE SATISFACTORY OPS CHECKS, NO DEFECTS NOTED. WORK PERFORMED IAW AMM 32-30-30.