W211 steering (rack) knocking

[L_A]

I have a knock coming when my steering is moved from left to right and can be more apparent when the power steering is not on and the steering is hard if I rock the steering right to left it will knock not sure if this is something to do with steering rack itself or rubber bushings that maybe located with the rack ??

I read somewhere that this maybe a possible recall on these models not sure where i stumbled across this information cant find it now??

Anyone advise onthis??