Check the ball joint -- jack tire free of the ground and pry up on the bottom of the tire, where it would contact the ground. Any vertical movement of the ball joint, replace it.

hard to see on a W123, but if the boot is torn, expect the joint to have failed.

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!