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