A factory tech might know if there is a n MB specific way, usually a close inspection with a good lighting and an adequate pry bar will reveal any looseness in the joint. If you have a lift you can get the car up and then use a tall stand under the suspension to then look at it without everything hanging as well. Without a lift you can jack the corner up enough to hang the tire a inch or two and then use a long lever to lift the tire from below while watching the ball joint move.