A method includes providing an elongated probe having a longitudinal axis and a distal end, and capable of rotation of the distal end about the longitudinal axis in mutually opposite first and second directions. While an operator manipulates the probe within a body of a patient, the rotation that is applied to the distal end is sensed automatically. An alert is issued to the operator upon sensing that the rotation is in the second direction, but not when the sensed rotation is in the first direction.