My wagon had been getting the rumbly creaky steering at low speed, complete with visible bubbling and frothing at the reservoir when turning the wheel. Time to reseal the pump.
As a short term solution until I got it done I swapped in a different one I found from an older 300D (65 bar)- one that provides a lower pressure than the pump for my '85 300TD (82 bar).
This made the steering too difficult to be deemed safe to drive. I just wanted to put that out there. I hadn't seen anything in my searches that stated the lower pressure pumps would or would not be alright to use in a newer 123 w/ the higher pressure pump.