Oki OKIFAX 5750 Service Manual page 846

Operation during Toner Low state
l
When the stirring bar reaches the maximum
height, it falls to the minimum height due to
its own weight, since there is no resistance
provided by the toner on the other side.
Because of this, the time interval during
which it is in encounter with the magnet of
the sensor plate becomes longer. By
monitoring this time interval, Toner Low
state can be detected.
Toner Full State