Abstract: A surgical handpiece (940) for actuating a cutting attachment (944). The handpiece includes a housing (942) which contains a motor (52) for driving the cutting attachment. A coupling assembly (948) releasably holds the cutting attachment to the housing and connects the attachment to the motor. A state marker, such as a magnet (1012), is disposed in the housing. The state marker is connected to the coupling assembly to undergo physical displacement when the coupling assembly is transitioned from the run state to the attachment release state. A sensor (960) monitors the physical displacement of the state marker. Whenever the state marker undergoes physical displacement, the output signal from the sensor changes. Thus, an external device can monitor when the handpiece coupling assembly (948) is transitioned from the run to the release state by monitoring the output signal from the sensor (960).