What was found
WHEN ELECTRICAL POWER TRANSFERED FROM GROUND POWER TO NR 1 GEN, POWER TRANSFER OCCURRED NORMALLY. DURING REMOVAL OF GROUND POWER, NR 1 GENERATOR FELL OFF LINE. ACFT GROUNDED. ACCOMPLISHED NR 1, NR 2 AND APU GCU BITE PROCEDURES REF MM 24-21, TASK 801. NO CURRENT FAULTS OR STORED FAULTS. ACCOMPLISHED AC POWER OPS TEST IAW MM 24-21-00, OPS NORMAL. UNABLE TO DUPLICATE PROBLEM. REPLACED NR 1 GENERATOR CONTROL BREAKER C801 IAW MM 24-21-41 AS A PRECAUTION. OPS NORMAL.