Hitachi DH 50MB Technical Data And Service Manual page 28

(Caution)
The factory-installed carbon brushes are not identical to each other as shown in Fig. 21. Pay attention to their
difference when reassembling after inspection. There is no problem when replacing them with a pair of carbon
brushes supplied as service parts (No. 77) because both parts are the same type (guide piece provided).
Handle
Housing
Carbon brush
Carbon brush
Guide piece provided
Guide piece not provided
Fig. 21
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