What was found
WITH LEFT THROTTLE ADVANCE FULL FORWARD, OBSERVED NO "TAKE CONFIG" LIGHT BOTH CAPT'S AND F/O, AND NO HORN, RIGHT THROTTLE OPS NORMAL. GROUNDED - YES. VERIFIED ORIGINAL DISCREPANCY, ONLY RIGHT HAND THROTTLE OPERATES NORMAL (LIGHTS AND HORN.) REMOVED AND REPLACED LEFT HAND AUTOTHROTTLE SWITCHPACK ASSEMBLY REF B737-900 AMM 76-11-07/401 OPS CHECK OK, GROUND VERIFICATION SUCCESSFUL.