I'm certain that many MB parts are designed to have an expected minimum life-span. I'm also certain that when the failure rate of any given part indicates a problem, MB orders that a failure analysis be carried out, and the MB Quality Evaluation Center (QEC) in Jacksonville, Fla., is given the task of figuring out what the problem is. It's doubtful though, that they'd be interested in sharing that information with the members of this Forum.