What was found
DURING MVF - VIBRATION COMING FROM LEFT ENGINE. HEARD LOW RUMBLE DURING TAKEOFF ROLL. AFTER ROTATION, WE COULD HEAR AND FEEL VIBRATION. WITH CONSTANT AIRSPEED DURING CLIMBOUT / CRUISE FLIGHT, WE MANIPULATED EACH POWER LEVER INDIVIDUALLY - LEFT ENGINE THROTTLE POWER UP / DOWN GREATLY CHANGED VIBRATION. RIGHT THROTTLE - NO CHANGE. REMOVED AND REPLACED NR 1 ENGINE STARTER/GEN AND OPS CHECKED GOOD. IAW AMM 24-31-01. NO DEFECTS NOTED AT THIS TIME.P/N 00SG180Q S/N S00297XL.