Abstract: A method, computer-readable medium, and storage device for detecting and compensating for a change in MR-offset in a disk-based storage device. A pattern is written to a track on a disk of the storage device utilizing a read/write head. The read channel of the storage device is then configured as a harmonic sensor and the pattern is read from the track at a specific off-track position of the read/write head. The magnitude of the harmonic sensor is measured during the read, and the change in MR-offset is calculated for the read/write head based on the measured magnitude value and a predetermined transfer function between off-track amount and harmonic sensor magnitude. The change in MR-offset may then be utilized by a servo mechanism of the storage device to correct head positioning during a write operation for the read/write head.