As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMBOUT OF FLIGHT 3108, F/O'S EADI AND EHSI SHOWED XXSIDE DATA ON INITIAL CLIMBOUT. HEADING BUG WOULD SHOW LEFT AND RIGHT 15 DEGREES. CAPT SIDE DATA WOULD CHANGE BETWEEN VOR AND LRN MODE. AIR RETURN TO MSP. MAINTENANCE REPLACED NR 2 DPU. NR 2 DPU OPS CHECKS GOOD IAW SF340 MM CHAP 34.