The present invention relates to the treatment, alleviation, prevention or reduction in the incidence of symptoms, diseases or conditions resulting from or associated with enteroviruses, more particularly the enteroviral infections they cause. A warning display member bearing information relating to manipulation of the control lever is detachably attached to the control lever in such a manner as to be removable from the control lever by pulling the warning display member generally in the same direction as manipulating the control lever to set the fixing unit to the pressing-contact state. The thumb bolt may be advanced by either turning the thumb bolt andor advancing the thumb bolt against a spring biased ratcheting mechanism.