Samsung CLX-8640 series Service Manual page 401

4. Troubleshooting
6) Check if gears below is broken or contaminated.
7) If the problem persists, replace the fuser unit(JC91-01120A(110V) / JC91-01121A(220V)).
8) If the problem persists, replace the Motor DC(JC31–00159A).
9) If the problem persists, replace the main board(JC92–02516A).
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