As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ELEC GEN SYS RT IDG HAS DISCONNECTED OR A PROTECTIVE TRIP OF THE GENERATOR CONTROL BREAKER HAS OCCURRED OR A PROTECTIVE TRIP OF THE BTB HAS OCCURRED. REPLACED RT ENG GCU WITH GCU SWAPPED FROM APU POSITION OPS CHECK OK, MSG CLEARED. (MR24241-74 NOW IN RT ENG POS, MR24241-35 IN APU POSITION).