It is caused by a possible collision between the patient and the rotating
arm. After having the patient removed from the system, press the patient
centering key to restart the power on procedure to correctly set the unit.

If the error message is again displayed, there is a fault on the rotation
sensing circuit and perform the following steps:

1. Check that rotation motor M3 is rotating; if not, check the cable from
the motor to Rotation Group board (A7), connector X61 up to the
main CPU board (A5), connector X25/X25.

2. If the motor is running, check the optical sensor B2 and its cables to
X60 of A7 up to connector X25/X26 of main CPU board (A5). Replace
the sensor or the faulty cables.