What was found
ON TAXI IN, AFTER SHUTTING DOWN NR 2 ENGINE, NO POWER TRANSFER. TRANSFER BUS OFF AND SOURCE OFF LIGHT ILLUMINATED. ACFT WOULD NOT ACCEPT GROUND POWER. APU STARTED AND POWER APPLIED NORMALLY. ACFT GROUNDED. RAN BOTH ENGINES AND TOGGLED NR 2 ENGINE GENERATOR AND GROUND POWER SEVERAL TIMES. TRANSFERRED NORMALLY. WHEN ENGINE NR 2 SHUTDOWN, POWER TRANSFERRED TO NR 1 BUS NORMALLY. GCUS SHOW NO FAULTS REF TASK 24-21, TASK 823, INTERMITTENT FAULT. REPLACED NR 2 BUS TIE BREAKER IAW MM 24-21-41 AS PRECAUTION. OPS CK GOOD IAW SAME.