There are a few electrical parts you should change as well - the rotating diodes that rectify the output should be replaced once you have access to them if they are original, as, when they fail they don't all fail at the same time, and the result is a very poor DC voltage control that will cause electrical unbalance problems that add load to the bearings and typically cause uneven wear of the commutator (called slip rings elsewhere - but it is the surface the brushes from the voltage regulator ride on).

Check the commutator surface for wear ridges and coning. If there is much more than 10 or so mils deep gouging or coning from one end to the other, repair is not likely to be very successful. Also, if the brushes on the voltage regulator are significantly different in length it is an indication you have electrical or mechanical imbalances that likely have already begun to wear the bearings and commutator surface unevenly.

Jim

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Own:
1986 Euro 190E 2.3-16 (291,000 miles),
1998 E300D TurboDiesel, 231,000 miles -purchased with 45,000,
1988 300E 5-speed 252,000 miles,
1983 240D 4-speed, purchased w/136,000, now with 222,000 miles.
2009 ML320CDI Bluetec, 89,000 miles

Owned:
1971 220D (250,000 miles plus, sold to father-in-law),
1975 240D (245,000 miles - died of body rot),
1991 350SD (176,560 miles, weakest Benz I have owned),
1999 C230 Sport (45,400 miles),
1982 240D (321,000 miles, put to sleep)