Replying to When is it time to replace a binding?

How do you decide whether or not to switch your old binding onto your new boards or buy something new?

I've got a pair Rossi Axial 14s that I've been using for years. The heel pieces don't snap into place on their own anymore... I have to bend down and lift them up with my hand. But I have never had a bad release either. Probably time to replace those, but in general how do you know when a binding is worn out?