A system for infallibly positioning a transducer on Track Zero on a flexible magnetic disk in the face of possible sensing errors by an optical Track Zero sensor customarily build into a disk drive. The transducer has not been correctly recalibrated if it has been positioned, when the disk drive is powered on, on an invalid track existing, either virtually or actually, immediately radially outwardly of Track Zero and if the disk drive is connected to a host that commands recalibration merely by causing transducer travel radially outwardly of the disk. A recalibration control circuit is therefore provided which cancels the host command and which, instead, causes the transducer to travel a predetermined distance radially inwardly of the disk and then to travel radially outwardly until the Track Zero sensor indicates again that the transducer is positioned on Track Zero.