Sorry I do not have a specific answer; there is nothing in the FSM concerning taking apart the Starter;or at least I have not discovered that section yet.
Nor have I ever seen specs for any other Starter in any of the books I have read concerning proper end play.
If those are the thrust washers to the right; perhaps you could swap the around so it/they do not ride on their already worn surface; until you get enough clearance so that it does not rub.
Apparently the rubbed area is not making any electrical contact with (+) currant and may not be causing any problems at all.
How about a pic of the end of the Starter that rubs on the plate.
In fact I would like to see pics of the whole Starter apart as I have not had any Mercedes Starter apart yet.
From the pics I have seen in books it looks extremly similar to a Delco made Starter.
