As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IRS L&R DRIFT APART. GROUNDED - YES. AIR TURNBACK - IAW CREW L-1R WAS 0.5NM AND R-1R WAS 14NM. L-1R WAS STILL SHOWING SFO AND WHILE FLYING. REST ADIRU AND 1R RADIAL POSITION ERROR CHECK IAW AMM 34-21-00-200-801, FOUND WITHIN LIMITS OF 0.3NM. AS A PRECAUTION REPLACED LH ADIRU PER AMM 34-21-01 OPS TEST OF ADIRU OK.