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, {HEAD ~ the locking} is released in {TAIL ~ response} to 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 , { HEAD ~ the locking } is released in { TAIL ~ response } to 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 HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH