The present invention generally relates to implants and, in particular, to systems and methods for monitoring the condition of an implant within a subject. The drive mechanism includes first and second drive units that can be selectively engaged to control the magnitude of the drive torque transferred and the relative rotary speed between the input shaft and the axleshafts. In the handle assembly, a combination lock is disposed adjacent to a cylinder lock in the handle. The laser scanner assembly would typically be part of a laser printer. Using the control channel indicator avoids unnecessary searching, saving time and resources in the location process, and increases the likelihood of successful call delivery.