When a sensor has detected that the amount of the developer remaining within the developing device has been reduced to an amount equal to or less than a predetermined amount, {TAIL ~ the locking} is released in response to {HEAD ~ a signal} from the sensor 
When a sensor has detected that the amount of the developer remaining within the developing device has been reduced to an amount equal to or less than a predetermined amount , { TAIL ~ the locking } is released in response to { HEAD ~ a signal } from the sensor
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH