What was found
FLT#1620, BOS-LHR. (ETOPS) 'AC GEN CLASS II MSG ( CLASS II MX MSG - GPCU OR AC GEN ); REMOVED AND REPLACED GCU # 2 PER TSM 24-22-00-810-832-A, VERIFIED BY GROUND CHECK AND OPC PROCEDURE IAW AMM 24-41-00. OPS CHECK WAS GOOD, NO MSGS WERE NOTED. MDDR ITEM RESTORED. MX-4 UPDATED, PLACARD REMOVED.' (SUPPLEMENTAL INFORMATION ADDED)