I can tell you that it is better that it not arm than to have it go off at some in-opertune moment. Like outside a motel at 6 in the morning.

I have never heard my '92 300E make any indication that it armed itself. It has, however, done the aforementioned.

There is a connection between worn tumblers or some other mechanism in the door locks to the alarm system. Have heard of people switching cylinders from Passenger to Driver side. Other than that I am clueless on this problem.

Steve