I have a medium stockman with carbon steel blades from the mid 80's. The main clip blade gets a "ding" right in the middle of the blade's edge upon closing the knife. The blades don't touch when closing them so that's not the culprit. The blade "kick" is plenty high to stop the blade from bottoming out against the backspring. If I push firmly down on the blade against the backspring's tension when it is closed there is a little downward movement before it bottoms out against the inside of the backspring. So I know there is room between the edge and backspring. How is this ''ding'' happening because it does not seem to come even close to the inside of the backspring upon closing? How can I stop it? It's real irritating to constantly fix the ''ding'' in my knife's edge every other day. Thanks.