Another MB trick is that when you have an alignment done, don't let them hook the steering wheel to the brake pedal. There's a cap somewhere on the steering box. Remove the cap and fit an appropriate size rod (screwdriver should do) into the hole and engage the slot in the steering shaft. That is the proper straight ahead setting. If the steering wheel is off, reset the steering wheel. Chances are you'll be forever correcting your alignment if you force an alignment without keying off the center position of the steering box.

Basic advice on this is let an MB dealership do the alignment or take it to someone who knows about locking the steering box. "Huh?" is your cue to go somewhere else.

Sixto
95 S420
87 300SDL