Folks have reported problems with play in the steering coupler (#23).
I have no play there at 200k, and I have not yet personally witnessed this problem on an assortment of other 124s.
Excess play in the steering box is common, and can be adjusted out. This can make for a gentle 'thud' if you turn the wheel abruptly.
The syptoms for either would be an unusual amount of free play in the steering before the steering linkage responds at all.
That diagram came courtesy of ************************:
Link
They have nice pictures, and very pretty catalogs, but the prices are generally higher.