The problem seems to be with the camera body; what could it be?

The problem seems to be with the camera body; what could it be?

For focusing to be accurate, the camera’s body dimensions/depth – or the measurements from lens mount to the plane of focus – must be correct to within a fraction of a millimetre. Correcting any anomalies with the dimensions could require a realignment or calibration of the mirrors or sensor, but if there is damage/distortion to the bayonet or internal frame of the camera, the affected parts will need to be replaced.