The engine manufacturer orderes by the bulletins SB-912-070 R1 and SB-912-070UL, inspection and / or replacement of the valve push rod assy., and rocker arm. Due to deviations in the manufacturing of the valve push rod assy., partial wear on the rocker arm ball socket may occur. This wear might lead to a rocker arm cracking / fracture which consequence may lead to a malfunction of the valve train. Possible effect are rough engine running or an unusual engine operating behaviour.