Oki C3520 - Manual (Page 95)

Maintenance > 95
6. Locate the two fasteners (a) at each side of the belt (b)
and the lifting bar (c) at the front. Turn the two fasteners
90° to the left. This will release the belt from the printer
chassis.
7. Pull the lifting bar (c) upwards so that belt tilts up towards
the front, and withdraw the belt unit from the printer.
a
a
b
c