What was found
ON FLT 400 - ATL-ATL - AIR RETURN, AFTER TAKEOFF CLIMB POWER WAS SET, THE NR 2 ENGINE BEGAN TO SURGE. EPR 1.5-1.7, F/F PLUS MINUS 1500 LBS/HR, EGT, N1, N2 ALSO FLUCTUATED. REPLACED PRBC AND P AND D VALVES IAW MM 73-10-2 (P AND D) AND 75-31-1 (PRBC), RAN NR 2 ENGINE IAW MM 71-00 OPS CHECKED GOOD.