What was found
AT 70 PERCENT NP, CAPTAIN'S AHARS GOES BLANK, THEN RETURNS WITH HDG FLAG AND COMPASS CARD 30 DEGREES OFF THE HEADING. RETURNED OT SAN. REPLACED NR 1 AHC-85. PERFORMED REORIENTATION PROCEDURE. RAN LEFT AND RIGHT ENGINES THROUGH 70 PERCENT NP, AUX GENS ON AND OFF, CAPTAIN'S EHSI AND EADI CHECK GOOD. OPS CHECKS GOOD, COMPASS CARDS AND HEADING MATCH SIDE TO SIDE.