Has anyone out there had any probs with the jack slipping out when changing the wheel.I am very experienced when it comes to most things motor wise.However while changing the off side front wheel the other day on a concrete garage floor , I went to offer the wheel up to the hub I reached across to pick up a stud the jack slipped out with no warning and trapped my hand between the wheel arch and the tyre.Trapped, a friend who was with me at the time had to re-position the jack and relieve the pressure.A visit to the hospital and one broken and dis-located finger later.Neither of us can work out what happened.No contact was made with the car (never got the chance).No one was in the car and the jack shot out sideways and landed about a foot away.Puzzled and wounded, wondering if anyone has had a similar experience