Only way for that to happen is not to have the cable inserted correctly and it slips loose as you release pressure on the first leg lift. I have almost started climbing and realized mine was not locked in place and fixed it before starting up. The pressure actually pulls the cables tighter when installed correctly. Impossible to slip backwards which is what has to happen for one to pop loose unless the locking tab has been removed or totally bent out of position. If that is the case it is user error.