A mandrel position analyzer (108) in an imaging device (100) includes a head stock (144) for a first side of the mandrel; a tail stock (104) for a second side of the mandrel; a first encoder (212) attached to the head stock adapted to measure first signals wherein the first signals are generated by movement of the mandrel; a second encoder (208) attached to the tail stock adapted to measure second signals wherein the second signals are generated by movement of the mandrel; an analyzer (224) which compares measured results of the first signals and results of the second signals; and if the measured results do not match generating an abnormal state of the mandrel signal alarm (260).