As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
PDX FLIGHT NR 2296: AFTER ENGINE START, FO NOTICED PUFF OF SMOKE BY NOSE AREA. ELECTRICAL PAGE SHOWED NO LOAD ON NR 1 TRU WITH .25 LOAD ON NR 2 TRU AND .5 LOAD ON BOTH GENERATORS. AIRCRAFT RETURNED TO BLOCK. MAINTENANCE REMOVED AND REPLACED NR 1 TRU IAW AMM 24-31-21. OPS CHECK GOOD. AIRCRAFT RETURNED TO SERVICE.