No need to tear the alternator apart. Either find a rebuilt one or buy a new one, that's the way to go.I wouldn't attempt to replace the bearings when I could put in a completely rebuilt unit. I've never had to look, but I'll bet that you could find a rebuilt one because there are a lot of our Mercedes engines out on the road.

A good way to detect bad bearings that's quite simple is to use a large screwdriver and put the blade on the alternator, while the engine is running, and put your ear to the handle. If the bearings are bad, the noise telegraphs up the handle and you can hear them rattling around. We used to use this method in the garage. Another way is to loosen the belt and spin the alternator, sometimes you can feel the grating of the bearings. Other causes of the noise could be from other devises driven by the serpentine belt such as the water pump or idler pulley or power steering pump.

I was hoping that the member who started this thread would have responded back to us after he took the car in to be repaired to let us know the outcome so that we could all learn something. Too many times I've seen posts asking for help and not giving us any feedback once their problem is solved. Good Luck with your problem. AND LET US KNOW THE OUTCOME. We need to build our data base for future searches.