Samsung SCX-8240NA-CAS - Manual (Page 193)

Troubleshooting_ 193
6. Insert the paper dust stick back.
7. Close the inner cover.
8. Pull the corresponding charger cleaner completely as shown below.
Do not strongly pull the charger cleaner to prevent it from
separating from the machine. It can cause damage to the
machine.
9. Push the corresponding charger cleaner completely as shown below.
Repeat step 8 and 9 five times.