Lower front pass side corner on the side of the housing. Something like a 17mm lock nut and the set screw is a 15mm?
I once bought a w115 240D w/ a "bad" transmission. All it needed was the screw turned in a few turns.

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Over 21 years I owned several:
w108
w110
w111
w115
w116
w123
w124
w126
w212