What was found
NR 2 ENG HIGH VIBRATION AT 4.0. NOTICED AFTER 80KTS. STAYED AT 4.0 IN AMBER. LEVELED AT 12000FT TO RUN QRH. AFTER RUNNING QRH STEPS ENG REMAINED 4.O - 4.2 AS WELL AS BEING ABLE TO FEEL A VIBRATION FROM THE ENG2 SIDE. ENG 2 DID RETURN TO GREEN WITH REDUCED THRUST SO WE KEPT IT REDUCED AND RETURNED TO DFW. DURING TAXI IN WE DID SEE A BRIEF RETURN TO 4.1 VIB IN ENG 2. TRANSFERRED TO NRWC 045-DFW-05383 ITEM-1. EMERGENCY DECLARED C/W E2 FAN BLADES AND PINS TROUBLESHOOTING IAW EA72-00-00-012 FOUND PINS NEEDED CHANGED REF NRWC 045-DFW-05384 FOR RAR OF PINS OPC CHECK GOOD HIGHEST VIB WAS 0.3AU @70% N1